I have realized that when I try to learn anything new (not just a language), I need to see examples and walk-throughs in order for me to comprehend the general rules of a system. It is only when I have an overall mental map of how a system works that I can start to fit the examples that I see into this model.
Learning Spanish while I was still living in England meant that I had to rely on using course books and language CDs rather than regularly meeting native Spanish speakers. At that point I did not know about the wonderful boost that a language exchange partner can give to your learning. I could have arrived in Spain with a much higher level if I had been meeting with someone to have regular Spanish conversation practice. Anyway, the books were my main resource and I did a bit of research to find a good Spanish grammar book that would explain the ‘rules’ of Spanish to me. The one I ended up buying was A New Reference Grammar of Modern Spanish (Amazon link). Here’ a short video of me flicking through my well worn copy showing some of the page contents.
I love this textbook. It is not too dry, but very comprehensive in its explanations, but above all it is stuffed full of example sentences taken from many different Spanish language books, newspapers, radio broadcasts and even conversations overheard on the street. The Spanish examples come from all over the world too, and the authors hi-light the fact that, for instance, a certain phrase comes from Argentina, and would not sound right if used in Spain.
Because of the diverse sources for their examples they are definitely not on the boring side. If you still need a Spanish grammar reference book (and if you are in anyway serious about learning the language you should have one) then have a read of the reviews on Amazon and see if you like the sound of it. Amazon allows you to read the first few pages on their site so you can get an idea of the readability of the text, and here is a photo of a typical page to give you an idea of the grammatical examples and style of writing.