BRG Wiki on Flyertalk

• You cannot BRG against a rate on a Starwood Website/App (hot escapes, promos, Gov. Rate etc.). It has to be a 3rd party website/App.
• Cancellation policy has no bearing on a BRG claim
• There's no need to reserve with SPG first.
• If you find a rate lower than the advertised SPG.com rate, then submit a BRG claim form. If it is approved, you will then have 24 hours to book on a Starwood Branded Website (SPG.com, Westin.com etc.) and reply to your pending approval email from BRG with the confirmation number.
• Make sure to book a flexible rate on SPG.com. This will allow you to then cancel this booking if you find a lower Starwood rate later (like the hot escapes etc.) or if your travel plans change.
• To save time, you can also book a flexible rate first on SPG.com, and then submit your BRG claim. This saves effort when filling in the BRG form, as well as the need to book within 24 hours of receiving the email from SPG. If your claim is not approved, simply cancel the flexible reservation.
• If your comparable rate includes extras like breakfast or parking, make sure there is a room available on spg.com that includes the exact amenities. If there is the same room type with the same amenities on SPG.com, they will compare and if lower on third party, the claim may be approved for the room type and with the amenities. If there is the same room type available but no/different amenities offered, the claim may still be approved, but the rate will be room only.
• Room types must be the same for a BRG. If you are trying to submit a BRG against an existing reservation, you will need to select “I have a Starwood reservation” on the first page and then select “My BRG claim is against the rate on this reservation” on the second page of the claim form. If you are looking at a different room type and rate than what you have booked on the Starwood site, you will still select “I have a Starwood reservation” on the first page and then enter the room type and rate you are seeing on the Starwood Website/App in the fields provided on the claim form. If you do not have an existing reservation booked with Starwood, you will fill out the claim form by selecting “I do not have a Starwood reservation” and proceed as normal.
• If you have an approved and finalized claim and you find an even cheaper rate later, then you may submit a new BRG claim that is not connected to any existing reservation. If this BRG claim is approved, you will need to make a new flexible reservation on SPG.com. Once the process is completed, you will then email the BRG desk to cancel your first reservation (which is flexible, although you can't cancel online).
• If you find availability for the room type you want on a third party website/app but there is no availability for that room type or no availability for any room type on the Starwood Website, then this may be an approved claim if it meets all other terms and conditions. You will need to make sure that you specify the room type you actually want on the Starwood Website section and enter 0 in the rate and currency. This will ensure that the processing associates know that the room type you want is not available on the Starwood Website. You may also add additional comments near the end of the claim form indicating that there is no availability on the Starwood Website to help clarify.

Differing currencies

• "The Best Rate Guarantee department will approve a claim if there is a difference of 2.5% or greater where the currencies are different or a difference of 1% or greater if the currencies are the same."

Link to T&C
https://www.starwoodhotels.com/bestrate/terms.html

Should you take points or the discounted rate?
2,000 Starpoints is worth approximately $40-50. So take points unless the 10% discount is more than $40-$50.

Generally, for 1 or 2 night stays you'll take points, and for longer stays you'll want the discount.

How to add a SNA to a BRG reservation
• Log into your SPG account
• Click on your stays to view our your current reservation
• Look for your BRG reservation and click on "send confirmation" link for the BRG reservation
• reload the page and you should be able to now select "apply SNA to this stay" link