I have never Ice fished there but my in laws own a place on Long and I open water fish both lakes...
They are both great lakes....and close enough you could hit them both in a day......
They have been planting Walleye consistently every year on Long lake...They have a very good lake association there..I have caught some big pike on Long while Smallmouth fishing....I have been hearing good things about Perch through the ice on Grand....There is a bait store right on 23 just south of Long lake...I can't remember the name of it but stop there they will be able to get you headed in the right direction..
I love fishing both of those lakes and it is a great area...Hideaway Bar has good burgers and cold beer..