Yessum, I normally have an Airbase in every border city and a couple in the capitol. I build more when Stealth comes into play, 'cause their range is so much better. I use Stealth Bombers (or B52's if I'm at a push) to go ahead of my main strike force and take out Towers and Castles, occasionally factories and Barracks's get the chope too.
Personally, I dont rate AA guns at all. Mainly because I have never seen them take down a Stealth Bomber, which pretty much means their lifespan is from Industrial->Modern/Early Info. ages. Buy into Biplanes, Fighters, Jet Fighters and the Super Dooper advanced model and you can take out anything you can click on.
On a completely different note...It really pisses me off when you do a bomber run, take out your targets and hang arround blowing enough stuff up before your planes run out of fuel. Then you go back to your army and start guiding them in, only to be bombed by your bombers doing a second trip. Damn them.