I've just come back from mine. I missed the welcome weekend had committed early (my first choice) and I'm glad I visited by myself. The dept organised a programming which had me meet with DGS, attend dept colloquium, meet my future supervisors (got two), campus tour and some time with grad students.
Having committed, I took the time to ask about dept culture etc and about the minutae of living in the city (recommendations for banking, food shopping etc and to look for a place to live.
My recommendation is simple...enjoy it, you earned it and they want you. Buy a hoodie, cap or whatever so when you get back in the fall it'll be broken in and you won't look a total newbie...in other words make yourself comfortable and hopefully make a good impression. Congratulations!