Wow, where does one start? The place is stuffed with monuments, big as it is. Depends whether you want intrepid (ie rambling over miles of moorland) or convenient (close to a road). I wouldn't miss the following:-

White Moor (serious trek)
Greywethers
Scorhill
Yellowmead
Merrivale Stone Rows/circle
Lakehead Hill
Down Tor
Brisworthy/Ringmoor

I reckon that's enough depending on how long you've got and how far you want to walk. I'm sure others will have lots more. Have fun!

Fernworthy and Assycombe are my recommendations.

Went for a long weekend a week back - lovely place, you'll love it!

We went to Merrivale (stone rows and circle) which is right near the road and very easy to find, and Fernworthy and Greywethers. Fernworthy is on the way to Greyweathers - both are well worth the journey, but it is a bit of a walk.

If you go to Fernworthy/Greywethers, be aware that when you get to the car park at the reservoir you can carry on driving right up to the forest and park there - it would have saved us nearly an hour walking round the reservoir if we'd known! I'd take an ordnance survey map for these two.

Wistman's Wood might not be neolithic (although there is a stone at the end of the wood), but it is well worth a visit.

Have a great time!

You need a year...

Most of the sites mentioned are Bronze Age, but there are a few, mostly quite ruined, Neolithic chambered tombs/long barrows scattered about. Spinsters' Rock is the most well known (but not on the Moor itself).http://www.themodernantiquarian.com/site/8536/dartmoor.html

I think White Tor is a Neolithic settlement site.