A basement can be a great place to spend time with your family and the right basement insulation is necessary to help make it a more comfortable environment. In most cases unfinished basements are quite simple to insulate with spray foam, whereas finished basements can most definitely still be insulated but are more challenging to gain access to the rim joist and walls.
Rim Joist Insulation
Insulating your basement rim joist with Icynene spray foam will give you the biggest bang for your buck as this is where most air leakage takes place in the foundation. Most rim joists are easily accessible in unfinished basements and in finished basements with drop ceilings. If the rim joist is not accessible, drywall would need to be removed to properly insulate it and the foam may need to be injected into the cavity instead of spraying it.
Basement Wall Insulation
If your basement is particularly cold and you spend a great amount of time down there, insulating basement walls may be beneficial as well. Studded walls of an unfinished basement can be sprayed with Icynene spray foam, and RetroFoam insulation would need to be injected into any existing walls where drywall is up.