We have visited the Basin Park several times on motorcycles and they do not have special rates for riders. However, they do have covered and gated parking for motorcycles in their lot down the street from the hotel. It's first come, first served and fills up early on weekends with motorcycle events. The hotel often has specials (lower prices or room upgrades) so it's worth liking their FB page and getting on their mailing list.
I do not believe they have special packages for motorcyclists. They do have other special packages for weekend trips, which may include dinners or massage visits.
Contact the hotel - However, I believe all the off site parking for guests of the hotel is free...
Get an answer from 1905 Basin Park Hotel staff and past guests.