There are all sorts of reasons to be happy about this, but I am really excited about 2: education, and civil liberties/personal freedoms. I put research funding under education, otherwise it would be on the list too. There are more, of course, and there are selfish reasons for my choices.
Like one of the things that I am personally hoping for is for congress to make good on a promise back in the 90's to double funding for fundamental sciences. The NIH got it money, but the NSF did not. I think that quite a few problems have come out of that discrepancy, and straightening it out will lead to another boom in technological advances. (Things really have slowed up over the past ~10 years.) I may come back to this.
In an extension of the personal freedoms thing I also have a hope that they will be able to stop corporate profiling of consumers. I hate the notion that every (credit/debit card) purchase I make is tracked and used against me somehow, but I really like using plastic and shopping/paying bills online. Republicans have made heavy use of such corporate machinery to target voters with specific issue mailers and the like. It's more than a little creepy.