I have mixed feelings about recommending amps to people. They give a list of things they want, but you never know how each want is weighted. So I will give you the ones I feel fall into the category of your wants.
Light weight, under 1000 bucks and 30 to 50 watts.
My first would be the Fender 65 Deluxe reissue. Yes it has only 22 watts but is a big 22 watts and fabulous tone. Reasonably light and good for the blues and classic rock. I take it you are looking for a combo, so my other recomendation is the Marshall JCM 2000 DSL 401. A 40 watt 1/12 with a switchable clean, gain, and high gain channels. Reverb, and reasonaly small package. Awsome tone. I am using it as a head only, through my 2/12 Avatar cab and it sounds great. Try to get one of the later issues because there was a heat problem with the first ones. Also usually under 800 bucks.