I'd take a couple of pieces of my own cookware so I was comparing apples with apples on timings and feel.

Boil water - Use measured amounts. You could probably use it to do recovery test with some ice.

Preheat times can vary a lot, perhaps an oven thermometer? If that's important to you..

I'd bake something simple in the oven, like a box mix. Or use things sold in tubes in the refrigerator cases (lots of them say Pillsbury). It will give you an answer about baking without effort and you can replicate the test with fair precision on every range you test.

I'll be interested in what others say. I wish you the best in your purchase.

On the first renovation 10 years ago, tested grills and saute speed on Viking and Wolf. Wolf won.

For a new kitchen, was able to visit Eurostoves and did stirfry and grilling on the Culinarian through the graciousness of Trevor Lawson. Also ran ovens to see how warm doors became. Steaks were ribeyes (wanted a fatty cut), stirfrys were chicken and shrimp). I had watched the Eurostoves videos and read much of the threads here; No surprises--went in postive towards the range; it performed exactly as I had expected (very hot on stirfry and fast heat recovery, grill performed well). Having Trevor in and out while we were playing helped a lot. He has clearly been around a lot of people learning about the range and his knowledge and experience helped; he also is a good reference for other kitchen appliances and is not exactly shy with his opinions.

I haven't done it yet, however, I'd make an omelet in my own pan to get a sense of the range of burner temps and the evenness of heat. It'd be tricky because I think being able to consistently create the perfect omelet - or crepe even - is a true measure of cooking prowess, as well as the appliance and cookware at hand. It's one of those things that looks easy, and should be easy to get right every time, but alas, it's not! It just so happens, with a yard full of chickens, we cook a lot of eggs here, so it is a perfect test for me. Ahh, if only I had enough faith in my skills to pull-off consistent results! Lol.

Also, to check burner precision and control, I'd try searing and cooking scallops on the cooktop. Or maybe finishing them on a French plate, if there is one. Scallops are so delicate, they don't take much time to cook through and they're easy to overdo, especially if your appliance isn't where you think it should be or as responsive as you'd expected.

I agree, it wouldn't hurt to time how long it takes for water to boil in the pot you use at home.

For the oven, I like the already-mentioned idea of cookies on a sheet and cakes from mixes if you are comparing ranges. Also - because we cook pizza regularly - I'd make a pizza and check for a crispy crust on the bottom, well-cooked toppings and center, and an even cook front to back.

The thermometer idea is another good one; although, I'd only use it to check the ovens for pre-heat and baking if you have a quality thermometer.

If there's a broiler, I'd try a thick cut of meat as well as a thin cut.

Obviously, it's all about matching the range to each of our needs. If you regularly make custard, bearnaise sauce, chocolate souffle, fruit pastries, or roast chicken, for example, by all means, cook/bake your thing!

I did not get to test my range but these are some things that I see might be a problem in hindsight.

Before you go-

I would first prioritize your needs. For me the oven is important. Others want high heat for the burners or have other priorities.

Take a hard look at your cookware if you haven't already. Understand the properties of the metal it is made of. Cookware is the interface of the food to heat and will extend the capabilities of any burner. Cookware with poor heat conduction will limit the function of any range. Most burners in prostyle ranges are wider so consider the shape of the cookware as well. It is also helpful to understand in buying bakeware. If you are testing high heat, you really can't use nonstick except maybe the newer ceramics that withstand high heat.

Understanding Stovetop Cookware

Materials-of-Cookware

For the oven, maybe take some cookie batter and put several pans in at once. Cookie sheets should be shiny and aluminum. Cookies can burn or cook unevenly in the best oven if you use dark or steel cookie sheets. If baking is your thing you might want to see how it bakes other things. Check how the convection works. If you haven't had it before, it is different brand to brand and a learning curve. There is a difference between just a fan and third element convection. Turn the oven on and check the door temp after one hour. Observe how much heat is put into the kitchen or on you if you are standing in front of it cooking. Check out the lighting in the oven. Does it glare and can you see what is cooking. If you have rolling racks, take them in and out. I change my racks around a lot so leave a rolling rack in the bottom but don't like them for the upper rack(s). Check out the broiler. Some infrared broilers are very narrow. I use my broiler for half sheets and it is not what I would choose. If you are grilling a couple of steaks or small amount of fish mostly it might be great.

For the burners, check how quickly the pan recovers when you add food*. Check how the pans fit the burners, especially a consideration if you use cast iron or steel or have small pans that allow the flame on high to wrap around the pan. This can be on open or sealed burners. Bring something starchy like a can of spaghettios and see if the burner will hold them on low without scorching. This can also be affected by the type of pan. A small LeCreuset being cast iron will hold the heat and be hotter than an aluminum or copper pan. Check the sensitivity of the knob in controlling the heat. Look at the grates and lift them. Check how the range is cleaned. This is very subjective.

Write a list ahead of time starting with looking over the range while it is cold and starting with things like putting your starchy item on to hold and preheating your oven. If you have a written list you won't forget anything and you can keep notes. also bring a camera.

These are all great suggestions - exactly what I was hoping for and very helpful. I definitely plan to bring my own cookware and give some thought to its characteristics when testing the range. I'm going to test time to boiling a standard amount of water, oven to temperature and even-ness of cooking multiple sheets of cookies. We make pizza often so I'm going to check this out along with some other items we make frequently (e.g. high heat roasted broccoli, salmon, etc.)

I've started a lengthy list of things to check out on the range before I start the range, after I start the burners/oven and things I'd like to cook and things to bring. All of a sudden I feel like I'm test driving a car! Maybe not a bad way to look at it....

I'm mostly a stovetop cook, oven on occasion, and not much broiler use, so I did a chicken/vegetable stir fry, which sealed the deal on my Bluestar.
I do agree with trinkette's suggestion of an omelette, which can be very finicky, luckily my Bluestar excels at omelets as well!
BTW the griddle has been my favorite thing about the range, which ironically, I never tested on a demo...

The test that kicked off the Blue Star craze was done by the original Food Network host David Rosengarten in 2003. This article was widely influential and very well respected.

It's out of date in terms of the range brands he discusses. But the basic tests outlined and the features to assess remain useful.

Here is a link that might be useful: A Range of Options