can anyone help with a USA registered vehicle in Spain?

Can't give you much help with specific companies, but are you *sure* you want to do this? It's a huge pain to move vehicles from the US to any EU countries. You'd have to get in inspected upon arrival to ensure it meets EU standards. If it was designed for the US, it won't meet EU standards and will therefore have to be modified (out of your pocket). This means that when you want to send it back to the US, you'll have to change all the lights, etc. again. It's much easier just to have vehicles in each country, given the cost of a motorcycle.

Well, in case anyone was wondering, I shipped the bike and it cost about two thousand dollars US including delivery to my brother-in-law's house in Spain. I kept it registered and tagged in the US and had no problems including when I was stopped at a random DUI checkpoint. So far I've been to the Barcelona Harley days and to France. This year I'm riding to Geneva. The process of shipping wasn't too bad but the company I used wouldn't give me a specific pick-up date from the port. If I had to do it again I would try to use a company from Spain and not the US, or deal directly with the shipping company. There seemed to be a lot of middle-men involved and that upped the price quite a bit. On the Spain end they seemed to be more professional.
Well worth it! If you see a Pennsylvania tag on a Harley in Spain say Hi!