For two people, I'd suggest staying in the 24' range, with a slideout. Carefully consider what your are going to do with it. We spend time on less than perfect roads, many times dirt. You want a well made unit or you will be forever tightening things up. Like the nuts that hold the box to the frame.
Storage is important, but carefully planned packing is more important. Don't take what you'll never need. You might have to take a few short trips to figure it out. I'd like to get rid of all our "hard" plates and cups and just use paper, but I haven't won that battle yet! This may sound weird, but make sure you're both comfy on the potty. I've been in a few units where it was a really tight fit. A walkaround bed is worth it's weight in gold. It's a pain to crawl over each other in the middle of the night. See if your bed will fit a true queen size mattress as opposed to the trailer queen, especially if you're over about 5'10". If you are planning on doing a lot of dry camping, try to get at least a 50 gallon tank. Maybe most important are the tires and wheels. Do a search here and on RV sites and you will find a great deal of disdain for ST rated tires. If you can get into a 16" rim that is compatible with LT E rated tires, go for it. ST tires flat out suck. With your truck, you can comfortably pull a 9-10,000 pound trailer on the stock hitch. You don't have to, of course, but the tools are there. That means you don't have to go with a lightweight trailer. Get one that is more substantial and that will last. Worry about the "fancy" things like color, fabric, and curtains last. Personally, I wish we didn't have any carpet in ours. If you can find an RV show, go to it and look around. Don't even look at the prices, just the floorplans and styles. Keep an eye out on Craigslist and eBay. You can find some really good deals on barely used units in this economy. There is a lot more info, so look around.
As far as brands, I've heard REALLY good things about Arctic Fox. Also, our friends had a really nice Nash that they used for years. Our 91 Wilderness is now in it's 18th year with friends. The Wildcat we have now is good, but I'm sure there are better out there.