We have stayed in Matagorda 3 times over last two years.
The commerical centre/shopping centre has at least 12 places to eat.
Try the Slowboat II and the greek one if still there, also the steakhouse on the inner side but really any of them are fine( the irish bar is overpriced, 3.5 per pint, upstairs it was 2.5euro. Even abroad the irish will try to ripe u off. The full breakfast in the swedish mans place in the morning was 2.80 and he has the morning papers, very popular.
Car hire is very cheap
Huge Hypermarket 10 mins towards Arreciefe on the left, or even bigger one on the farside of Arreciefe , do the week shop there if self catering. The local supermarkets in the various hotels are expensive.
its a far walk to PdeC, taxi up and stroll back, PdeC is getting a bit tired loking.
If in to seafood, try the Village of El Giffo, way down the other end of the island, faboulse food and scenery.
For huge steaks try the Lanais resturentant chain, can be a bit busy
Cannot think of any down side other than the large irish pub, there is a smaller one on the outer Airport side of the Commerical centre. And yes walk the broadwalk about 10mins from the centre, and u can stand under the incoming aircraft as they go over head by about 50feet, its awesome.
Sept should be lovely time.
good luck