If you want to stay right near SFMM we always stay at the Hilton Garden Inn Valencia which is basically at the bottom of the entrance hill to SFMM.
http://www.hiltongardeninn.com/en/gi/hotels/index.jhtml?moreDesc=true&ctyhocn=VALVHGI
If you want a more "centrally located" hotel between SFMM and Knotts or Disney you'll need local recommendation. We either stay at that hilton or at a hotel near Disney but not in between
Heidi
Edited to add this information about the fast pass's at SFMM
FAST LANE PASSES
Shorter Lines...Limited Waiting...No Kidding!
Fast Lane passes can be purchased for $15 at the ticket booths, the Fast Lane booth (behind Guest Relations in Six Flags Plaza) or at the Guest Necessities Center.
A limited number of Fast Lane passes are available for purchase each operating day.
The passes will be available only while supplies last and are valid only on the day of purchase.
The rides available for Fast Lane vary from day-to-day (please check with the host/hostess at the Fast Lane booth for a list of specific rides available for Fast Lane that day).
Each FAST LANE pass is good for four priority boarding opportunities: 1 person x 4 rides, 2 people x 2 rides, 4 people x 1 ride ... it's your choice!
The FAST LANE program does not require any sort of reservation or pre-determined arrival time. Simply choose your ride and follow the FAST LANE direction.
Also if you are going before April 30th they have a deal on the SF website that you can buy them online and they have to be used before the 30th of April for a price of $29.99 where regular prices at the "door" are 46.99 for just MM or 56.99 for MM and HH and Parking is an additional $8.00.
Starting in April the park is open every day with different hours. Also April 17-18 is a drill team competition so if you go beware it is CROWDED~! We did that once for a cheerleading competition...oh my lord! I think we rode 4 rides all day long from opening to closing!!