I've been using water based lacquer from Target Coatings. It's very easy to work with, washes up with warm water, no VOCs and fully cures in 4 days. Sands and buffs to a beautiful deep shine. It's more durable than nitro, too.
For a sunburst, after sealing and applying the lightest color, I spray TransTint dyes in DNA. It's very easy to control, can be sprayed fairly wet without sags or runs and builds color slowly so you have alot of control.
My most recent using this process...
Peace,
Mark