Puppy classes are a great idea, because as someone said earlier (Penny I think) the mental stimulation will help wear her out! Is it a clicker class? Clickers are a great tool for helping to train dogs, and really easy to use, you can set aside time at home (just half an hour here and there), to do exercises with her
You could try making her work harder for her food.. So instead of feeding her from a bowl, soak the kibble and put it in a kong, or place in a treat ball/bottle (like Rachel suggested). You can also wrap food in rags, tie knots in it and layer it to make it harder for her to open, if you put a piece of cheese in or sausage it'll make it more interesting to her then just kibble.
All these ideas are designed to make her think, use her doggy instincts and basically wear her out. As at the moment her efforts are driving you mad. I have a really great book called 'The Culture Clash' by Jean Donaldson, it describes the dog as having a 'tank' of energy that has to used up, the more you can syphon into 'good' activity, the less bad things will happen!!
The most important thing to remember is that she's not doing this to annoy you, upset you or because she is 'knows' it's bad, she just wants your attention. Use your time outs and also make her use her energy in a constructive way (not on your cupboards) and it will get better... Promise, cross my heart!