Monticello is the ideal place to explore eastern Utah from.  Everything is about an hour away.  National Parks and monuments: Moab, Arches, Canyonlands, Hovenweep, Monument Valley, Canyons of the Ancients, even Mesa Verde is close.  Moab is an hour away.  Cortez, CO is an hour away if you need recreational, um, tobacco.  It's also a lot less crowded than other places in the high season.

Old West RV Park, plunked down right in the middle of Monticello, is owned and run by "Big Jim," an avuncular trick shooter who regularly gives a show to the occupants of the 15 or so rigs that fit in his park. 

Good Verizon coverage; the campground has wifi but it doesn't stretch out to the end.  We were in space 12; Big Jim seemed to think it was not the best spot (no wifi), but we liked it because our door opened onto a view across the street instead of the side of another trailer.

The park will fit any size trailer if you can get one of the few pull-through spots.  Other spaces, like ours, will fit pretty big trailers (ours is 25-ft) but you will have to unhitch and park next to your rig.  There are full hookups and everything is in good order.

NOTE: the water pressure is quite high.  They will lend you a pressure regulator for free or they will sell you one for $15.

We really enjoyed our four days here and would definitely visit again.