reply to nyrrule27
Re: Paint a room. primer or no primer I'm painting stained trim around my house. I went and bought Sherwin Williams expensive primer and trim paint...
What I found is that i have to prime 2X, sometimes 3X, allowing a day between coats to get effective blocking of the colored stain. Then I then need 1-2 coats of white gloss trim paint to get a consistent looking white cover. In one case the tanins from the wood still bled through after a few weeks so I needed yet another re-coat of trim.
For my porch door I decided to use Behr Ultra Primer+Paint exterior paint (white) because I had some left over from doing the door jambs (which were already painted white). I primed first with SW because it was handy, next day it was the typical color bleeding in various spots... I decided to go straight for the Behr at this point, and I was surprised to see after a day no color bleeding... a week later... still nothing. When I did the interior trim for the door I just used straight Behr paint... it seems to be doing a great job (after a week) of staying adhered to the previously stained surface and had good coverage.
So I think those primer + paints can be good at sticking, coverage, and consistency. If I hadn't already painted every room in my house I would certainly be considering them.