When I bought direct, the Guide tried to fast-talk me with numbers to get me to buy the newest resort (which would pay him more commission, I imagine) rather than the old sold-out resort that I wanted. So be prepared for the Guide to tell you that it would be more cost-effective for you to buy Riviera because the contract will expire in the year 2070 (as opposed to SSR for which the contract will expire in the year 2054).
You need to remember why you want SSR rather than Riviera. You don't need to tell the Guide your reasoning, but you need to know what it is so that you stick to your guns.
(For example, perhaps you will be 90 years old by the time SSR expires and you don't have any kids to leave the contract to, so you don't really care about the 16 extra years you would get on the Riviera contract, but you will get that argument from the Guide anyway.)