BTW, those 7-night certificates can be upgraded to stays at higher category hotels for additional Marriott points. They can also be refunded (before they expire) if you don't use them. They'd be treated as cat 1 hotel certificates (7.5K per day for 6 days) for refund purpose. So you'll receive 45K Marriott points (or 15K SPG points).

If you're not going to use the hotel certificate, the economics boils down to 80K SPG points for 130K AS miles (in a direct transfer to VX) or 75K SPG points for 120K AS miles (in an indirect transfer via Marriott). The former is slightly better (5K SPG points to 10K AS miles) in that scenario.