Ti can be fantastic for Ultra Distance, as well as touring, both light and heavy. Find a maker that can select the tubeset for how you want the bike to handle and "feel" - and include mounting points for racks and fenders. You may also want to choose long reach or canti brakes, to allow clearance for fenders and wider tires.
I've a carbon frame that I used for a full brevet series this year - it worked well - but I used clip on fenders, was limited to rear rack only, and couldn't mount tires larger than 25's, clearance being the issue between the frame and the tire. I've used it for short hops to friends, but I'd be hesitant to put it through a weeklong or monthlong or longer tour.
I'm partial to the IF Club Racer - which can work for light touring and my everyday riding, including brevets - there are plenty of makers out there doing things similar - including Rivendell, Waterford, and in Ti I think you could even get something from Litespeed.
Remember that if your doing LD riding, wether it is heavy or light touring or brevets and randonee's, that long term comfort is important - that may or may not include things like options for fenders and wider tires. If you're on tour and moving fast - you may have to ride in the rain 2-3 days in a row - and fenders will certainly help here - and likewise one of the first things you can do for day in day out riding it to use slightly wider tires - more air = more suspension on rough roads - I vary between some nice 25's and 28's.
So long. Been nice knowing you BF.... to all the friends I've made here and in real life... its been great. But this place needs an enema.