Marriott RI allows points/nights for long stays. Starwood gives no points/nights/stay credit at all for any stay (as they define it) that exceeds 90 days or 3 months, not even for the initial period.

Something else to think about is taxes on hotel rooms. In many USA jurisdictions, you can avoid paying them for stays over 30 days or 1 month, although you may be required to sign a lease. If you check out (versus just periodically pay the bill) or switch rooms, the 30 days/1 month starts all over again. Sometimes it can be cheaper to pay for the room continuously, including weekends when you're elsewhere.