Dianne,
I've actually had a bit of experience with both German and Spanish. I began learning basic Spanish in 3rd grade, and continued it all the way through high school. However, when looking into college, I decided to enroll in an International Engineering Program with German as the language instead of Spanish, to try something new. I took 3 years of German courses in college, and am now spending my 4th year studying abroad and interning in Germany. I've been here for about 9 months now, and have 3 more to go.
As far as which language is easier to learn, I felt as though Spanish was much easier to pick up. Even still, after 4 years of not speaking it, I've forgotten nearly everything. German has been a bit more difficult for me due to the difference in sentence structure and all of the adjective endings and the such. There's a whole lot to think about! But, if you put in the effort, it's more than doable.
Even though German has been tougher to learn, I actually like it a lot more. There are so many options if you are looking for a German engineering job or internship. As an added bonus, Germany is an awesome country, and a beautiful place to spend some time. I would definately recommend it!
As you mentioned, since being here, I've seen that most of the young German people can speak English. Nearly all of the college-aged students speak almost perfect english. But, With the older generations, that is not usually the case. German also comes in handy in other countries. While the dialect is much different, we had no trouble getting around Austria and Switzerland. Even in the Netherlands we could pick up a lot of words. But, if we were ever really stuck, someone around knew English. I have not been to Spain yet (will soon.....Malaga this weekend!), but many of my friends have. They said that it seemed like far less people in Spain knew English than people in Germany do. So, while Germany may be easy to survive in without German, Spain sounds harder to survive in without Spanish.
It's such a hard choice between the two languages, but I love Germany and would never change my decision.
Good luck with yours!
Brad