The honeymoon suite is great. The jacuzzi tub is huge (for two), and the king size bed is really nice. We were on the non-MK side, but we still felt very secluded. I agree with the other poster that you should ask for the MK side if it is available. You might be able to see the fireworks at the MK. Bring candles and wine!
My husband and I honeymooned at WL in January, 1997, and we didn't find any problems with the transportation. Boats take you to the MK, and buses take you to the rest of the world. We never had any problems in mid-January with crowds. (We went back to WDW for our anniversary in 2001, but we didn't stay at WL. We did confirm that mid-January is a great time for a WDW vacation!)
Even if you stay at a monorail hotel, you still have to take buses to Downtown Disney. One monorail loop takes you to the MK, the Contemporary Resort, the Grand Floridian Resort, the Polynesian Resort, and the ticket and transportation center (TTC). The other loop only stops at the TTC and Epcot. For example, to go from the Grand Floridian Resort to Epcot, you have to stop at the TTC and change monorails. (Someone please correct me if I am wrong!)
Just a thought...If you are looking for a resort with a good "adult location", check out the Yacht & Beach Club Resorts. We found ourselves at the World Showcase of Epcot every night on our last trip, eating and drinking our way around the "world". Y&BC Resorts give you easy access to the World Showcase as well as the Boardwalk (resaurants and clubs). It seems like Epcot is the park that is open the latest, but you could confirm that. (For example, during our last trip, in January, 2001, I think that the MK closed at 7 PM or so, but Epcot didn't close until after 9 PM.)
I hope that helps! Enjoy!