A couple of thoughts - first many of us equate Spanish & Tapas with the magic word
fresh as in all ingredients - frozen fish or frozen vegies just never cuts it - so availablitity and price are going to play some part in your planning a menu. Can (or do you want) to change your selections based on time of year (hot-cold- unbelievably cold and "gawd-awful"
Chicago -correct?)
Detail the area of the city where you plan to locate the tapas bar - how health conscious is it - in other words - do the folks eat meat or will the bulk of the clientele be quasi vegitarian?
Penelope Casas has some brilliant cook books on Spanish food - I'm not suggesting you read them as a chef but more for an insight different areas of the country, etc
Marketing - be it homework for the menu or coming up with a logo is, as you know - crucial .... good luck and keep us posted