There seems to be some confusion about whether it is better to use the Marriott Visa or purchase the Marriott GC's through the UR mall when in truth it is a pretty straightforward calculation:

Marriott Visa $1000 hotel spend = 10000 + 5000 CC bonus + 5000 elite bonus (assuming platinum status) = 20,000 points

UR Mall $1000 in Marriott GC's = 5000 + 4000 bonus UR points + 15000 Marriott points for the same stay (also assuming platinum status) = 24,000 points

It seems like you would get an extra 20% Marriott points in total by going through the process of buying the gift cards through Staples, so long as the bonus levels stay as they currently are.