Visa services
 

Haven't seen any recent posts on visa services - which ones are most reliable these days? One of the travelers is on Chinese passport (with US GC) - not sure is that complicates/delays invites etc docs and processing. Can prob do a normal path with hotel invite etc but if some service can take care of all that stuff it may be worth a premium (plus add flexibility to change hotels if better options come along later).
How far in advance is it worth applying?