Memorial Drive and Storrow Drive both have low bridges that frequently snag trucks. So the best route for a truck to the Hyatt Regency Cambridge hotel from the Interstates appears to be:

Mass Pike (I-90):

Mass Pike to Exit 18 (East Bound) or Exit 20 (West Bound)
Go toward Cambridge (cross the river)
River Street to Central Square
Right on Mass Ave
Right on Vassar Street
Left at Hyatt

If you're coming from North or South of Boston, take I-93 to the Mass Pike and then follow the Mass Pike directions. The Mass Pike for a 24' truck (two axles) is $1.25 from I-93 to exit 20.