Go for the Dob!!
If you reckon the 8 or 10-inch Dobs are too big, get one of these ultra-portable 5-inch Dobs:
http://www.ozscopes.com.au/skywatche...telescope.html
Be sure to hook up with people who can help you collimate it so you get the most out of it. (If you buy from a non-online competent telescope vendor like Bintel, they'll do that for you.)
But I bet soon you'll be hankering for more! Still, the 5-ich SW dob could be a nice one to have to take with you wherever whenever even if you decide to get a bigger scope later.
I had a 102mm Skywatcher Mak. Good scopes. But on the night sky they run out of steam very quickly. Good for birdwatching (with an erecting prism). The 90mm will be even more lacklustre.