Carol and I did both this year as she has never been to YS. Beartooth highway (212) out of the NE exit on the way to Glacier is an absolute must.
Had my Nikon spotter along with a 24x fixed WA lens but never broke it out.
We got the mileage out of binos along, but YMMV. Would consider a 10 or 12x with an exit pupil of 5 or so, to pick up on the on the low light side of things and a quick connect tripod for long viewing.
