Well Hello There,
The Requirements for SPG Gold are 25 nights or 10 stays, and Platinum is 50 nights or 25 stays. If you are traveling a lot for 1 night at a time then 25 nights for gold is the best way. If you travel for 3+ nights at a time in general then stays are better. Yep, thats right, Gold SPG does not get lounge access like marriott however the requirements for gold spg are less than marriott.
"A stay could have more than 1 night, but how would you have a stay and not a night? " It wouldn't