Depends on how far you need to travel. I'm spoiled here on Vancouver Island for bears. But like to milk it out for more enjoyment. I know my areas very well, can get there in 3 hours, but still like to take at least 3 days to hunt. Will do this several times in the season.
If I had to travel greater distance for bears, I'd treat it like any other hunt and go for at least a week or more.
OP, I agree rainy days suck and you have to deal with the weather you have. But bears are voracious in the spring and will feed throughout the day regardless of weather. As long as you aren't fogged in or have a real low ceiling, glass west, south-west facing slopes. I camp where I can glass several slopes. Makes passing a crappy weather day more tolerable and productive. Rain or shine, you should be able to find them. And for me, wet pissy days that clear in late afternoon/early evening are money days!!!!