There's a lot of, I think, unjustified fear about St Leonards. I grew up in Hastings and my mum lives about 5 minutes from that house. So - I am biased!
There is no doubt that there are really shabby areas, but genuinely there are some streets which wouldn't look out of place in the sharper parts of West London.
Big houses, wide streets, garden squares, two minutes from the beach. St Leonards has a bit of a trendy enclave (Norman Road), funky cafes, over priced antique shops. (also tramps, drug addicts, peeling paint but there you go)
I visited mum a couple of weeks ago and went to a 'Jumble Sale' in a school hall. Dahling you couldn't move for lovely trendy mummies and their vintage wares, all very friendly and warm (and selling overpriced vintage but there you go).
Go on and see it on a crisp sunny winter morning. Ramble around and then have tea in the Old Town. So much for your money and as someone who once lived on the dodgiest estate in south London, the crime and shabbiness isn't any concern.
Let me know if you want more pointers as to where to go!