The month of May is a great month for bass fishing. May is a bank beater's month of months. There are fish all over the banks and they can be caught on just about anything. I consider the month of May post-spawn because there aren't many fish still on the beds, but there are fish all over the lake guarding their fry.
If you have never seen bass fry, they start out looking like something you stirred up from the bottom with the trolling motor. You can move a bait through them and see the cloud of thousands of baby bass moving away from your bait. Once they get a little bigger, you can actually tell they are fish and if you catch one in a net, you can even tell it is a bass - even at less than half an inch.
The neat thing about finding bass fry is that they wouldn't be there unless they were protected by an adult bass. Turtles and perch are their main predators and the adult bass can always be found near the fry keeping them safe from their attackers.
My main baits in May are flukes, wacky worms, Texas rigged worms, chatterbaits, and topwaters. I think the fluke is probably the best bait since it stays suspended in the fry for a good while. During this time, there are so many fish guarding fry that you will probably be throwing close to more than you realize, assuming you are fishing the banks and fishing around some cover. May will have lots of cloudy/rainy days, so topwaters are great this time of the year.
May will also still have some spawning bass lingering. Sometimes it is worth looking for bedding bass and sometimes there aren't any to be found. They spawn in waves and just because you don't find any on beds doesn't mean they are all finished spawning. Just about the time you think it is over, another wave starts. I expect to find some big bass on beds in the first half of May. But once the water gets that warm, the fish don't stay long. A female may move up on a bed in the morning and be gone by afternoon.
Near the end of May, the post-spawn bass will start migrating to their summer patterns and at the same time we will likely have more sunny days and less cloudy/rainy days. This is when I also make my transition. It is now time to fish at night.
The good thing about post-spawn is that you can catch lots of decent size bass. The bad thing is that the females are now smaller because they lost their eggs. Also, the majority of females are still recuperating from the spawn and not biting very well. Most of the fish you catch in May will be males - they are primarily the ones that guard the fry. This is frustrating to me because in April I catch big females basically every trip. On the up side, June is right around the corner. That is my best month for catching big fish at night.