Hi Lorna, congrats on visiting Cuba. And good luck with your return trip. Here are some interesting places for you to consider.
Bayamo has a nice boulevard with bars and clubs. It’s a fun town and well off the tourist trail.
Playa Larga has more tourism but there is snorkeling and diving and the town is quaint. Not lively, but small and local.
Cienfuegos is a larger city but a lot of fun. It is also close to the El Nicho natural park where you can see waterfalls and swim in lagoons.
Cardenas, right beside varadero can be fun. Despite it’s proximity to varadero, it is not touristy at all.
Pinar del Rio is a nice small town, close to Vinales. Again, not touristy at all.
I like Las Tunas and Manzanillo, but they are not particularly lively places. TBH, most of the residents of those towns would say that the towns are terribly boring, but I enjoy them because there are few tourists and have an authentic Cuban soul.
I hope this helps and if you have more questions, just ask.