One of our favourites is La Caja De Las Tapas in the Charco de San Ginés area – I’m not saying it’s the best, it’s just that it was so nice the first time and we keep going back when we’re looking for lunch in Arrecife. It’s near the sculpture of (I think) a whale’s skeleton.
For something a bit different, try Castillo de San José. Restored (inevitably!) by César Manrique, it is now an art gallery (itself well worth seeing) and restaurant. The restaurant is lovely and the food excellent, great for a special lunch if you’re in the area, with views over the harbour (we were there when the Queen Victoria was berthed opposite). To get there, from the marina, turn right and keep the sea on your right, following signs for the port (Los Marmoles).
Another great place – primarily for the 360 degree view – is the cafe on at the top of the Gran Hotel. Coffee and cake there may not be the cheapest, but it’s worth it for that view.