So it only makes sense, the more important your fort gets, the more temp. visitors you should get.
These could include more liasons and diplomats, no doubt, to hold important meetings and such. But I was thinking...
Once you've got a monarch, it only makes sense that you'd be VERY important with other races, and especially other dwarven civs if they're arround. So periodically, with trading caravans, or with their own little entourage, visitors may arrive.
These may require high standard rooms. Therefore, bedrooms would be assignable to VIP1. Once you assign a bedroom to VIP1, VIP2 would be available, and so on and so forth.
Upon these visitors arriving, they would claim one of the VIP suites available, then run around conducting meetings and such. It would be assumed they were important guests and as such would be exept from any economic charges etc, they'd only get food and drink anyway.
As DF progresses and we get guilds and religions and stuff active properly then that adds more scope for visitors.
You might get a foreign monarch, a notable craftsperson or tradesperson, a diplomat, a legendary warrior, religious leader,etc. etc.
Basically, they'd probably meet important people, especially nobles, or crafts people they needed to talk to, or religous gatherings, or whatever. They'd spread the news of your fortress when they left too, depending on how good their stay was, and the benefits of having them there may include making your dwarves super happy, or giving them exp. boost from talking with a master of their trade, or giving something for your nobles to do, everything really. Possibilities are huuuuuge!
Of course, there'd be downsides too. If some Human King arrives, meets your King, looks round the fort, has a few meetings, attend a royal banguet, falls in love with UristcGoldigger, generally having a great time, then walks outside and promplty gets shot by a soon-to-be !!Kobold Assasin!! then the Humies might... well, not like you much.