Ultimately, that's up to you! It's your home and your poster, and you're given freedom in how you want to present and preserve it. It's a way to show your love for the series and your place in life. To ensure longevity, I always recommend a frame, and as a flip side, it helps give the posters a more mature and modern feel. A few years ago, I used to rent a room in a house, and since I was younger and living paycheck to paycheck, I couldn't afford frames for my posters. As I grew older, I felt that it gave my room more of a dormitory feel than the feeling of a man in his mid-late twenties. To make matters worse, when it came time to move, I found that my posters had gotten damaged throughout the years, and I could not store and transport them to my new living situation properly. Framing them would have kept them in tip-top shape and given me a safer way to store them so I could display them in a new home.