I was gold for a few years and have been plat for a few years. I haven't seen a big difference in upgrades. It strikes me that upgrades depend more on the hotel and the length of your stay than they do on the difference between gold and plat. One colleague of mine, who's gold, gets more upgrades than me at the same properties. He's typically staying for 1 night at a time whereas I'm often staying for 4-5 nights.
The platinum check-in amenity is nice overseas. I usually get a small snack and 1-2 bottles of beer or 1/2 bottle of wine. That saves me upwards of $25 at FS restaurant prices.
In the USA I usually take the points.
The increase to 50% bonus points is nice. As Jerseygirl17 showed, it can be worth a few awards nights per year.
The 48 hour guarantee is nice. I have used it twice this year. Both times it enabled me to stay multiple nights in a desirable location without having to hop between hotels.
These benefits are all nice, but one always has to ask,
compared to what? If the alternative to MR Plat is MR Gold + low tier in another hotel program, I would generally take MR Plat. If the alternative were MR Gold + Gold (middle tier) in another program, I'd consider the dual Gold route. Analyze your travel patterns to understand your realistic alternatives.