I'm always ready to eschew the virtues of Santa Eulalia, IMO it is one of the nicest places to be in Ibiza. It is within easy reach of most places except San Antonio which I don't like much anyway. It is a working Spanish town which stays open all year round so tourists mix with locals just about everywhere except for the dreadful English bars in the town.
There are excellent restaurants here and one of the nicest cocktail bars on the Island (Liquido) which is situated in the Marina, has excellent views, comfy sofas and plays mostly laid back Spanish house music. Oh one other bonus - we don't allow kids in so you can drink all night in peace.
As for hotels most customers rave about Ses Estaques because they don't allow kids under sixteen there and Tres Torres because it has views across the marina and is an easy walk into town.
As to eating and drinking, well you can get most of anything at varying prices. The Spanish bars all do menu del dias from between eight and ten euros or you can go upmarket and spend around twenty euros each on a two course meal. Wine prices obviously vary but you can get drinkable wines in most places for ten to twelve euros a bottle and under. If you really want to push the boat out we sell Cristal champagne for €220 a bottle which is €200 euros a bottle less than the nightclubs!
Sunbeds are €3 a day. If you do end up in SE then avoid the excursions to the Hippy Markets, the hotels charged fifteen euros this year and you can get a bus from behind the town hall for seventy cents. I don't know a lot about any other excursions, but I am sure that there are plenty.
Santa Eulalia is a more expensive destination than Cala Llonga or Es Cana but then it is a lot more sophisticated.
Please ask if you have any other specific questions.