You can arrange a vehicle to Ceibal by road these days, but boats went slow and fast. It may still be the same by boat. Faster is better.
Aguateca is relatively close to the water, but Dos Pilas is not. Dos Pilas will take you a few hours on foot after the boat ride.
There seem to be two recognized hotels in Sayaxche, the Guayacan and something else, whose name I don't remember. The other one is likely to be the better buy though.
Viajes Don Pedro in Sayaxche is the place to arrange your ruin trips.
