Laminate can work in your situation, but you run the risk of moisture damage to the laminate from surface water and condensation between the laminate and the vapor barrier...the dew point will be reached at some point and 'solid' water is the usual result. You may also get condensation between the vapor barrier and the OSB. I don't think it's a good idea, but other professionals may disagree.

Laminate or wood would be a poor choice. Carpet, porcelain tile or stone are good choices. There is a new product out now called Konecto that would probably work well.

Do not use laminate wood in uncontrolled enviroments where temperature humidity will fluctuate alot (like pseudo-indoor/outdoor areas), especially if your walls are only windows with little to no insulation or set r factors for insulating purposes. If the area is as well insulated as the rest of your home then go for it, but since you stated temp is an issue, then I advise against it.

I would go with an indoor/outdoor carpeting, or a ceramic or stone tile system over a membrane allowing for uncoupling, load-distribution, water/moisture resistance, and vapor management properties like Schluter Ditra that is made for pseudo outdoor/indoor areas. Do not use standard cement or fiber backerboard units.

Konnecto needs to maintain temperature through its life like most other resilient products, so that would also be an impractical choice.

What about those sheets of vinyl made by Armstrong that look like wood planks? Has anyone seen those in person? I was considering that type of flooring for my own sunroom.

I'm not really interested in tile or stone. Just too hard a surface and I really hate grout. I hadn't heard before about vinyl plank flooring. I've been searching the archives in this forum as well as online and I like the look of the vinyl planks as well as the Konecto product that jerry_t mentioned (what exactly is Konecto though -- linoleum or ?). Has anyone tried either of these options in a similar setting? I suppose that vinyl sheet flooring in a wood pattern could work as well but suspect that sheet vinyl would look like sheet vinyl and not wood. Since the patio room was just completed, I don't know what to expect as far as temperature goes but do think heat could be an issue. The room is surrounded on three sides by the exterior house walls (located in a U of the house) with one side of the room being glass. Any comments much appreciated.

I installed a vinyl tile (these days called LVT...laminated vinyl tile) in a converted deck/three season room in New Hampshire. It's gone through two summers and two winters with nary a problem. The product was installed over 1/2" underlayment grade plywood and I used flooring epoxy to adhere the tile to the plywood. The product is a commercial LVT by Toli. You need a well-constructed product with some 'body' is my thought here. There are many candidates in the marketplace by names such as Amtico, Karndean, Toli, just to name a few. LVT is surprisingly 'not' cheap...and flooring epoxy isn't either.

Flooring epoxy is difficult to work with and really should only be attempted by a professional, but...if you're smart and can purchase the right tools, trowels, hand roller and rent a 100 lb. flooring roller...I guess you could DIY successfully. You do have to follow all label instructions to the letter.

That said there are many indoor/outdoor flooring options available.