Burma is one place in SE Asia where a local private guide just for yourself can really add a lot to the trip and end up saving you a lot of hassles, even you just engage somebody for a day or so in a limited geographic area. They'll know some optimum spots that you'd not find on your own, plus deal with language issues. I say this to you as a confirmed independent, anti-tour-group traveler with a lot of experience traveling in all the mainland SE Asian countries.

The Bagan touting scene is nowhere close to what you find at Angkor, and even the most crowded sunset photo-taking spot in Bagan is not going to be like the sunset circus you'd find at Angkor's Phnom Bakheng. There just aren't that many tourists floating around Burma--especially in the last 3 years or so--and if you go outside the Dec-Feb "high season," it will be even more sparsely attended.