I always liked the idea of skill total areas, and skilling areas in general, Wilderness territory fort is my favorite place in rscr.
Max however is only a small portion of players. We already have the Legend guild at 1400 skill total, when the legends guild quest is inevitably released I really think a new area should take it's place focused more on the requirement, 1400 skill total. There are 18 skills currently, meaning it's fair to say the average 1400 skill total player has all skills 70+ with a few 99's How about an area focused on skilling level 70+?
If you want to go farther, Especially when slayer is released (Oh the rumors) how about a 1600 skill total area, which right now is 89+ all skills but whenever in the future another skill is added it will be 85+ (also the 1400 skill total will have to be amped to 1450 and altered maybe with a slayer area... but thats off topic.) This second part may be redundant, but it could be a room with more perks, similar to how the mining guild is a branch of the dwarven mine with a higher requirement.
I've made areas like this before, if you like I could post some screenshots, keep in mind though whatever the mods add here will obviously be different. Visuals I have are from long dead servers.
Edit: I love the fort... but it is DEFINATLY not a guild, it's a TEAM TERRITORY. You do not even get your own loot unless you're an officer or higher, or someone is on to give you your items. The only similarities of the fort and this suggestion are maybe a fire/range, anvil, furnace, and spinning wheel. Everything else there contributes to the Territory chest.
Edit #2: Off topic, but I was thinking of a money sink that would allow you to pay GP and have drops transferred to a chest similar to the fort (only outside wild) Something like 100k for 30 mins, 250k for 2 hours. Could make skilling and farming stuff like limpwort roots less of a hassle, at the cost of less profit from selling, or a fee if you're farming items to keep. Now that he said it's like the fort outside wild that made me think of this again.