I enjoy the completion of building side of things the most. I get the same looks when I buy lego - Moms normally talk to me about getting the right mini figs by "feeling up" the bags. As I am 35 the people in the local toy shop have got to know that stuff is for me and not for my non existent kids. I play with my nephew but prefer to just look at the stuff I've made and work out if I can improve it with better pieces or what vig I could build that hasnt' been done a thousand times before
. I spent my entire childhood playing with lego and Star Wars stuff, often wishing I could have things that there just wasn't the money to get. So now I guess I just like being able to both buy anything pretty much I want and then just admire it. I used to collect Vintage carded Star Wars figures but in comparison LEGO is just sooo much more affordable.