My tips would be:
1) avoid hotels in capital cities, or at least don't pick those in center
2) pick countries with mountains, otherwise landscapes in this time of the year are quite bleak
3) UK, Switzerland and Nordic countries are most expensive. Slovakia have beautiful mountains, so do Austria but its much more expensive.
4) general rule everywhere around EU - people under 30 will speak English, at least most of them a little bit
5) I would not recommend south states (Italy, Greece etc) as you will miss half of its beauty in winter
6) You can find nice architecture in most of the countries, but for nice nature I would head more east
7) as for culture, I don't know man I don't think you will find most Europeans that different from US but it depends on which people you will meet and where, don't expect to understand or even notice different culture when you are in big cities
don't miss Amsterdam, its a must! xD
If you choose to visit Czech rep, let me know, I can give you some specific tips.
Enjoy your stay!