Once you enter the special exhibit section, you can stay for as long as you like. No one is going to come and kick you out. So if you get in by 5:30pm (I believe the timed entry is every 30 minutes), you can stay until closing if you wish.

We took the #21 there and #5 back. I recall seeing some lovely Victorian houses on the way there on #21 but not the #5 route on return.

SAB, I see your point and I apologize. Did not mean to hurt anybody's feelings.

janis, I'm not sure about weekends. In any case, now you know your options. Personally, unless it were raining I would take the N because I find it quicker, less herky-jerky and generally more pleasant. You could google map 9th and Irving and then 8th and Fulton to get an idea of the difference in distance and how you would walk through the park. But any of the discussed lines will get you there.

Have fun!