Costa del sol.

Southern Spain or southern Portugal.

Even Greece can be a little chilly in April - too cold to swim normally. Crete etc. will be a little warmer than further north.

Have you considered Morocco? Safe, and reliably better weather. You can rent an amazing place there for not much money. We rented a villa near essaouira which was great - jardin des douars. But travel there is a little trickier than Europe, for sure.

OP here - - thought about Greece but may be a bit ambitious for our group. In my previous travels to Greece I found that outside Athens and the touristy islands, language can be a real barrier. Also travel there is a bit longer/harder. But I will propose it to the group as an option. Ideas for places in Greece? I know the islands but what about the Peloponnesse?