The Craven collection, Pendine, and the Bubblecar Museum have all been on my radar for the last few years, but I've haven't yet made it. The Dave Silvers Museum looks like a goodun as well.
Usually if I'm in an area, I try to visit the local military museum for a day. These are always great, and I've been as far as Bodmin, Brecon, Perth, Carlisle, Belfast, Enniskillen, Richmond N.York, Alnick, York etc
We have a fascinating little National Trust place near us called Patterson's Spade Mill. Definitely the last working spademill in the UK and Ireland, and possibly the world! The NT warden is an ex road racer, and a real character. He takes you through the whole process starting with a billet of steel, and then using a massive trip hammer and associated machinery driven off belts from a lay shaft, makes a spade in front of you. Originally it would have had a waterwheel, but a water turbine was installed in Victorian times, and is still used to this day. You can buy a finished spade as a working tool, or as a nice momento of a lost craft. In fact, we might visit here on our Shepherds Rest rally at Easter

We're a diverse bunch on this forum, with a broad geographical spread, so just a suggestion, but why don't each of us post up some details of an interesting local museum or place of interest on this thread?