I just had a bad experience in booking a 5 night cert/airline miles package. MVCI rep said the room I wanted to use the cert for was available and for the dates I wanted, so I went ahead. She debited the 430K points and took my airline FF information. She said she would get a Marriott rep on the phone to book the nights. Instead, she just transferred me to Marriott, where they told me that they didn't actually have the room available (except I could get a 2 night suite for almost 1M points). Reversing the transaction has been a lot of wasted time (case numbers and escalations -- not done yet). Some of this may because you have to get the 5 might awards from MVCI, not Marriott. My advice would be to book the room first, and have a confirmation number, before you get the certificate. Only Marriott can make Titanium seem more like "Tin"!