1. The option to return to a guild hall by default after coming back up from the Clockworks

I don't understand why the option isn't already in the game. Plenty of us run or belong to guilds with Halls having nearly all the features you could want from Haven and really no reason to go there unless we want a longer loading time.
You could even make it something you have to pay for by adding two small elevator additions near the main lobby.

2. An interactive bulletin board accessible to every member

More shocked this wasn't a thing starting day one of the introduction of guild halls than my first suggestion. TONS of us have announcements to make, events to host, things to request help for and many other things to plan but nowhere to do something like that. The MotD doesn't come close to cutting it either. Lots of possibilities here.

3. Battle Sprite Laboratory Room

Complete with Sprite Food Alchemy Machine and harness merchant.

4. Supply Depot, Token Trader and random Vendor NPCs

:v

5. Sparring Area in the Guild Training Hall

A small zone inside the GTH you step into where friendly-fire is activated and you're able to fight 1on1 with your fellow guild members. I guarantee a lot of the big players would get a kick out of this and would make the GTH one of the most sought-after reasons for having a Guild Hall.

6. Much greater furniture catalog

There's a very limited selection and has been for awhile and the most simple things like chairs cost a limb. Put some actual thought into the prices of each individual piece.

7. Some optional scenic additions

Remember the original guild hall? Before we were able to get ones we could do anything with? Had that cool little overhang showing off the interior of Cradle. Sure you could do something really neat. The Snipe Garden could be considered one of these.

8. Ability to add notes when donating funds or materials to the treasury

Small thing but I've heard some of our members would like to specify what their donations should be spent on.

9. Punctuation and other characters in guild names

Our guild ended up purchasing a Guild Name Change Ticket only then to find out we couldn't even use a period, comma or ampersand. We were REALLY relying on that "&" to use in our new guild name and it'd be nice to at least have some confirmation from OOO if it's possible to do such a thing or if it just isn't supported for some other reason. Bit of cash wasted.

Guilds are supposed to be about community and the current available features don't allow for absolutely any of it. Some of these should've been an option from the start and while we don't necessarily need the entirety of Haven in one area.
Why not.
More $$$ for OOO by adding some very simple things. You guys seem to take the easy way out with some of your content and I'd gladly pay a fortune for something I already have. Just in a new package to share with our guild. Make them all massive crown sinks, I don't care just give the halls a little attention again aside from stuffing game assets into promo boxes and calling it new content.