My .02
Below is my post on a related topic from a thread a while back on the EAA forums.
http://eaaforums.org/showthread.php?1316-What-tents-for-Oshkosh&highlight=Tent
As someone who has been in the Outdoor industry for almost 20 years, it amazes me that aviation enthusiasts who spend thousands on annuals and parts measured in $1k increments are not willing to spend the money it takes to buy equipment that will ensure a comfortable camping experience. Having recently lost my job due to "downsizing," I have no loyalty to any specific company , but can hopefully shed some light on what to look for when buying a tent.
The comment regarding mountaineering-oriented tents is a good starting point, but what you need for something like Oshkosh is known as a 3-season backpacking tent. Non-negotiable features should include: aluminum poles, not fiberglass (although carbon fiber is on the horizon but will be expensive, of course); a full rain fly that extends almost to the ground; fully seam taped floor and rain fly; as much no-see-um mesh as possible for maximum ventilation in the humid climate.
Some other considerations: Unless weight is an absolute consideration, buy one size larger than you need, i.e. a 3-person for 2-person camping. It will add about a pound, but give you way more space to move around and keep your stuff dry in a downpour. A vestibule is nice - it adds space covered by the rain fly but outside the living space, perfect for wet shoes, or even cooking if necessary. Windows in the rain fly are nice but not critical. The rain fly is necessary even in clear weather due to dew in the humid climate of OSH.
When setting up, stake out the rain fly as much as possible to maximize air flow underneath. If its clear, you can leave the door open, but anything exposed will get wet from dew.
To address the other comments: unfortunately the skills and knowledge required to sew complex products has all but been lost in the US, at any price. Also, the high quality fabrics required for lightweight, truly waterproof tents are mostly produced in Taiwan, even for domestic production. However, the design, development, sourcing, marketing, customer service and distribution of outdoor products still supports a great deal of good paying US jobs... hopefully to soon include a new one for me so I don't have to sell my RV!
That was it from the quote, but also wanted to add that Thermarest pads are the bomb... Way more comfortable than a cot. Go for the thicker. I used a 1" think one for years of backpacking but updated to a 2" one for last years Oshkosh and it was MUCH better.