Not sure if this is helpful, but I have 2 Valiant vines and I don't do anything to them, just let them ramble up a 3-wire support, then they continue up onto the fence and into the nearby trees. In the spring I prune out dead wood and canes growing where I don't want them to, and shorten things up a bit. They are so vigorous that about twice a year I go after them with hedge shears so I can maintin access to that part of the garden. Maybe you can do the same for your arbor, just pruning with shears when things get unwieldy and you need to shape the vine? Don't cut to the ground, you need some of that old wood to provide the new fruiting growth. A photo showing the grape at the back of the garden covering it's support, the 6-ft fence, and then heading up into a nearby apple tree:

So how do we know that the drop match is 27 inches? How long is your bathroom. How wide is your bathroom? Did you arrive at the 27 feet by adding the four walls? If so, then multiplying by the 8-ft ceiling is correct. JMHO, but whoever wants to sell you 7 double rolls is wanting to sell more and whomever told you 3-1/2 double rolls (or 7 single rolls) is probably wrong. I think 5 double rolls is about right. Each wallpaper bolt (2 single rolls in most cases, 3 in very odd cases) will tell you what area in square feet it covers. Now if you have tile on the walls, you can subtract for that. If you have doors, windows, you can subtract for that. I just did a friend's 240 square ft bathroom using 5 double rolls and she had a 23-inch repeat. We had paper left over, about 1 double roll. Another factor is the paperhanger. Some will try to save your paper, whereas others will cut one length at a time and not care about wasting it. Good paperhangers, all, does not matter, will waste or save. I am going to say your wallpaper store probably is the most correct. Most companies encourage you to buy more for waste as sometimes, even experienced paper hangers will measure wrong, cut wrong, etc., and then if you have to order more paper, there is that chance the dye lots will not match.

Thanks for all of the very helpful replies. You've given me much to consider. I'm quickly learning that in shopping around, you aren't necessarily comparing apples to apples, and you really have to know what level of insurance you desire and you need to know what all of the "add-ons" that they often package together actually are. I find this all incredibly dull and tedious, but also recognize that it is of the utmost importance. We have been with Farmers for many years, working with the same agent (not broker; I see pros and cons of using a broker). I'm old-school enough to place value on the relationship that has been established with this agent's office. It's just really nice to be able to call his office and have his long-time assistant know exactly who I am (and I know her). After looking at a few other quotes, it appears that we will likely just stay where we are. We have excellent coverage with a company we trust, so while the premiums have risen, I do understand that there are outlying factors that are not within our control affecting these costs. We will still discuss possible ways of lowering our premium with our agent, but I have a feeling it will just mean taking away certain coverages, and I know we won't want to go there.

Plus room to stand bent over with your head down beside the tub to clean behind it. Maybe the width of your vacuum cleaner head? I love the look, but I am too old to clean in awkward places. I would probably fall in the tub. I am so jealous that you get a freestanding tub! They are so beautiful.