If you've got film that was exposed 25 years ago , you need to get it developed first to see if anything is even useable .
Don't waste money on high quality scans on all of before you see them .
Maybe have them developed and scanned at a low ( cheapest ) option , or develop and print at 6x4 .
You can expect colour shifts , some tones missing etc .
Think '70's enprints !
If there's anything worth scanning , then get the negatives scanned .
High resolution scans aren't cheap , especially if you've a lot of film .
There's a good chance 90% of what's on them aren't much more use than just scanning at a low resolution and keeping for memories sake .
If the film was stored well in a fridge / freezer , the captured exposures might still be if good enough quality to print big , but I'd be surprised.
Personally , I'd develop them then either batch scan on a flatbed scanners or use a digital camera and take it from there .