hurricanebertha, dont worry too much...things will happen on their own. The thing with Angel Falls is that you need to get on a plane to get there, either from Ciudad Bolivar to Canaima or from some other village -sorry dont remember the name now- to Canaima. I dont think you can buy the plane tickets on your own AND save money, so in the end it pays off to go with an agency.
About not booking the hotel in advance...well, I never did the whole time I was there -and I was carrying one months' cash in my bra!! But never had any problem. I guess you'll only need to book in advance if you're planning on going to Caracas. Otherwise you'll be fine. Just try not to arrive into a town after dark and look for a hotel, and you'll be ok.
