"Going Global" is the legacy name for what Hilton now calls "VIP awards" which are available to Silver, Gold & Diamond HHonors members, of which every HGVC member is at least Silver. They require a minimum 4-Night stay and _can_ be booked online, but to get the system to apply the VIP-rate, you must sign-in to your HHonors account before beginning a search.
You can tell if you are being quoted a VIP-rate if you see it listed in the search criteria or if the point-quote for the property shows less than the standard-rate. You only need to call HHonors if you're not sure that the 'puter is giving you the discounted rate.
But yeah, converting HGVC points to HHonors points is usually a bad deal. Run the numbers: 1200 HGVC points will get you 3-4 nights at a HGVC resort, but convert to HHonors at a rate of 1:25 and you have 30K HHonors points, which may not be enuff for 1-N at a Hampton Inn in the boondocks. Also: You can only convert _next_ year's points and they won't post to your HHonors account until January.
You can use this year's HGVC points for a direct hotel booking, but you'll only get an effective conversion rate of 1:20, an even worse deal.
Bottom Line: HGVC points are best used for their primary purpose: Booking TS's at Hilton or RCI resorts (thru Hilton). OTOH, converting points you may lose otherwise, to get to the VIP award level needed for a posh hotel in a big-city, can make sense.