Planing a trip to Ramstein Germany for cousin in the Air Force. Any travel tips?

So my cousin just finished his basic training in the Air Force and will be stationed at Ramstein AFB in Germany when he begins his first tour at the end of this year. He will be stationed there for 1 year and then gets to choose where he wants to go. I have been to several European countries, but never Germany and I definitely want to take this opportunity to see it. I already have plans to take the bullet train from Ramstein area to Paris, which is only a 2 1/2 hour trip. I've been to Paris once before a couple summers ago and want to go back.

Have any of you ever been to Germany and can offer suggestions on places to go? There's not a lot near Ramstein. I'd be going with a couple other family members and we will be flying into Frankfurt. Ramstein isn't that close to Berlin but anyone ever been to Berlin before think its worth going to? Also, any other places? Like the German Alps or Munich? I'm just thinking of a good itinerary to have while I go to take advantage of while I'm there. Air fares are cheap (about $800 round trip) that I've seen so far from Philly to Frankfurt and I'd be staying on base, which will also be inexpensive. I'm thinking of going around this time next year. I don't want it to be super hot when I go but not really cold. Colder weather means I'd need to pack heavier clothes so I'd rather go when I don't need heavy sweaters and scarves and gloves and crap. So I'd like to maybe go with some long sleeved button downs with bringing 1 or 2 light jackets. It will be at least a 2 week trip. I'm so excited. Any travel tips would be greatly appreciated.

P.S. Not sure if this is the right group to post this in, but the Int'l Section doesn't have a Europe group.