I've had my '99 ST since early 2001 and still love it. It's had a few small mod's over the years and the sum of them is that, in value for money terms, there is nothing out there that comes close to achieving what I want from a bike in the same way as my trusty old Trumpet.
In 2007 a party of five of us toured Northern Germany, taking in a day at the Nurburgring, and the true nature of my ST shone through; all day comfort, 50+ mpg, up to 200 miles from a tankfull and the ability to scratch with (and often beat) the sports bikes I was touring with.
Here's a few mod's that have made a difference: Extended height touring screen - the standard one is c##p for fast distance stuff as was the d/bubble I tried. 'Genmar' bar-risers - adds greatly to the comfort, especialy at town speeds. Heated grips - essential if, like me, you prefer to wear lightweight gloves to retain feel. K & N Air filter. 'Splitfire' Spark plugs - even quicker pick-up from that wonderfull triple-pot motor. Triumph 'race' can and a session on a rolling road - it's improved the top-end performance considerably and on full chat it's the throatiest howl you'll hear this side of a Hammer horror flick, legal too.
The early ST's i.e. mine, made a claimed 108bhp. The 'race' can was the first mod' fitted and the R/Road showed 112bhp at 8,200rpm at the end of the session. I reckon, based on many miles running with mates on more poweful and newer stuff, that with the other bits added, mine must now be around 115 bhp+.
Yes, the styling may be questionable, the suspension isn't the absolute Dogs' and the engine likes it's 10/40 (about 0.5 litre per 1,000 miles if/when she's thrashed) but it boils down to this: Every time I get seduced into looking at some new shiny stuff, and even trying them out sometimes, this happens: Afterwards I have a coffee, then I think about it, work out the finances while drinking more coffee, then I think about it some more and then, on the way home on the Trumpet ..... 'What am I doing! The eight-and-a-half grand plus I'm gonna spend on that Yamasukihondaducatguzziumph buys me a lot of motorcycling holidays for a long time to come, using the bike I've already got. Which is pretty nigh perfect. So calm down, save your money, and run that Triumph until it doesn't tick the boxes anymore.'
It could be a while yet.