No special goals - maybe just a bigger discount at the resorts. Is it a big jump from 4* to 5* and is that worth anything?
I became 5* for the SPG Platinum, 10% SP bonus, and Elite Waitlist. The SPG Platinum benefits are fantastic and we have gotten a lot of tangible and intangible value from it at hotels. However, with the SPG/Marriott Rewards program consolidation coming in 2019, it's tough to say how much value there will be going forward. The 10% SP bonus is nice, but I've never actually converted my ownerships since I can typically rent them for more than the value of the SPs. As for the Elite Waitlist? Well, it's been proven here on TUG that it doesn't actually work.
Although I'm happy with my mix of developer and resale ownerships, and feel I have gotten good value from my Elite benefits, if I were considering 5* today with the knowledge I have now, I would recommend against it. Whether it's going to continue to be worth the tens of thousands it will cost to get there in addition to the ongoing maintenance fee bill is hard to say.