First off, here's a little about me: I'm a Marriott Platinum Elite and a Diamond VIP member. All of my stays are leisure. It's a stress relief method to get-a-way!
Here are my tips:
1) Always go on line and see if a particular suite is available right before checking in. That way, you can see if the room is available at check in.
2) If you are told there are no upgrades available, beeline to the business center and see for yourself. DO NOT HESITATE TO NOTIFY THE FRONT DESK AGENT OF THE AVAILABILITY! Do this without alerting the front desk staff of your intentions! Then, drop it on them!
3) If none are available, and the concierge lounge is closed, ask for a breakfast, dinner, and/or appetizer coupon(sometimes this might need approval of the supervisor on duty)...That might make you feel a little better since you can't get that upgrade.
4) Tell the GM, Sales Director, or front desk agent you will post a guest review of your stay.
5) The front desk agents always check the computer to see if you have stayed there before and which room you were assigned to, along with your profile request information. They will try to reassign you to the same room or room type if you do not request otherwise.
6) If you are a returning guest, hotel staff are more likely to upgrade based on your stay history with them.
7) Oftentimes, the best rooms are not advertised online, or shown as available, DO ASK FOR THEM!
I have stayed in Presidential suites, Ambassador, Executive suites, and bi-level suites, JUST FOR THE ASKING! And, I always pay the lowest standard/basic room rate!!
P.S. If you use these tips, please let me hear from you!