I have also had good luck with calling bears.
I have had bears pop up instantly and also called for 4 hours in a spot before one showed.
If you are calling blind then I recommend at least an hour. I call for up to 45 seconds, get a breath and do it again.
I prefer a Burnham Bros. Long Range C-3, but have also had luck with their Black Magic call.
I have also tried the Carlton bear call with know success, but the video is awsome! (maybe I haven't used it enough)
Last year while skirting a herd of elk I decided to use my cow call and called a 250 pounder within 35 yards before taking him. (not bad for a Washington bear in Aug.)
I would suggest that you reread all the above posts (including mine), then forget them.
No seriously, you will find that everyone's experiences are different and they may not work in your situation, but keep them in mind.
ROCKYMTNELKSTALKER - I have used the kissing/sucking noises to fool many a coyote and one nice 3 point blacktail.