All Mountain. In seasons past Ive just been going down the mountain but Im going to Colorado for spring break and Im gonna have my friend start teaching me in the park. So I'd like a board that covers it all. If possible something around $300
Burtonx8 is right ... this is rule number one on getting gear... you can get good boards and bindings cheap at end of year sales... take that savings and invest in quality boots. Do not just buy an expensive or inexpensive pair online. Go to your local shop tell them your size and riding style and try on everything... it may a cheap boot that works for you it may not but in the end having a boot that works for you will make you better because youll be more comfortable on the hill.
also boot brands size different so keep that in mind.. I wear anyting from a 9.5 to a 10.5 depending on the brand and my normal street shoes are 11's
Also, 300 is on the low side price-wise, but in my opinion a solid board for all mountain in that price range is the Sierra Crew. Right now its about 250 bucks. You may need the wide depending on the size of the new boots. The sierra crew is also very similar to the Burton Custom.
It would be fine for kickers, but if you're looking to do rails/boxes/buttering I'd look at something else. I ride a park specific board that also holds an edge well, but maybe someone else can chime in here on something that would work well for everything, the board I ride is a bit out of your price range.