I visited a few weeks ago, on a weekday. Very enjoyable, concentrating on the landscapes so you will not see some other famous works (sunflowers series). No queues/crowds to speak of (perhaps avoiding by entering around lunchtime!

Booked both travel and museum entry via SBB.

Can't advise on tours, however, informative notes (including English translation) are included in some rooms of the exhibit.

Enjoy your trip!