Trish. You could consider Rabat as an alternative to Valetta. It's a large town, not a city, but then not everyone would call Valletta a city! I believe Rabat does have a weekly market, but don't hold me to that! It does have OK parking though. Very easy to walk into Mdina and some good cafes etc.
The area I, personally, would avoid is around St. Paul's Bay. I'm a country girl who also loves the coast, but that area does not appeal at all. If you are into night life, clubs and lots of shopping Malta possibly isn't for you. As Tom says, it is all about the people and the country. The people are wonderful.
Weather is a particularly difficult issue this year. We are still struggling with a late winter in UK right now. I'm due to go BVI at the end of the week (a time we have visited for the last 10+ years) and the weather out there is not good. You have to make the decision no take chances don't you? Enjoy Malta whatever! I'm sure you will.