Welcome, good luck and have fun with your adventure. Buying an RV is a fun adventure and if you hit most of your goals/wants/needs then your camping experience will be fun as well.
Sounds like you've already given it some thought on sleeping and privacy. Other things to consider is time spent inside the unit, access to bathroom and impact on others, counter space, seating for dining, storage space, etc. The best thing to do is visit a number of dealerships and spend some time sitting in a variety of units and acting out using it. Thinking about what you'll take and where you put it.
Give some thought to what type of camping/rving experience you want. Some national park sites can get tight up around the 30 foot plus mark. Will you mainly do full hookup or at least partial hookup sites? These things are impacted by battery storage space, inverter or not, fresh water, grey water and black water holding capacity.
Give some thought to tow vehicle. The size and weight of the trailer will determine what type and size of vehicle your need for towing. Payload on the tow vehicle is the key number. Dry weight of the trailer advertised by the dealer is always a good deal lower than your actual weight.
You search the forums for threads on the above topics (plus pricing) and how others have made their decisions.
The best advice though, don't get excited and jump on the first unit that strikes your fancy. Once you purchase you will not be recouping your purchase price on sale or trade. You want to make sure the money difference between purchase and sale of the trailer buys you a tool to get the experiences you want. It may seem daunting as you get into to it. But the purchase process is fun. Just have set what are your must have's and like to have's and be ready to negotiate for your best value.
2010 Sabre 30BHDS: 10 gal elct/gas dsi, 15k a/c, 1.5 bath, high fidelity package
2010 GMC Sierra 2500HD 4x4, 1 dog, 1 wife, 2 kids, 2 cats