We went to Guatemala last year. I personally don't think you would need a guide to get around - some rudimentary Spanish and a decent guidebook should give you all that you want. There are 3 hotels in the Tikal area itself. All are pretty basic (i.e. little or no a/c), expensive for what they are and being in the middle of jungle are very buggy. A fun experience for one night and Tikal is really worth it, but do remember to take LOTS of insect repellent.
There are minibuses running to and from Flores throughout the day so there is no reason why you couldn't make it a day trip. Accomodation standards are a bit higher and much cheaper. It's a nice place to hang for a day, but no more.