Sustainable power in watts or better yet weight scaled watts per kilogram varies, but unless you're very light I'd guess 200 watts for 90 minutes is a modest workout for someone who averaged 34kph for an ironman bike leg.
Check out the information here: Power Profiling
In particular download one of those Excel power profiling charts. They're built for bike racers, but give weight scaled sustainable power for various durations of interest from world class cyclists down to untrained cylists so you should be able to get a handle on where you fit. The last two columns, 5min and full hour power are the most relevant for multisport athletes, especially the last.
There's plenty of good info on power training, levels and how to work with power data on other sections of that same site: Power 411, How to train with WKO+ Software and a power meter
FWIW, I'm a mid level masters racer and don't do any multisport but do a fair number of time trials each year. I have reasonable success with a bit over 4 watts per kg for my FTP (hour power) during the season. Last season that was roughly 305 watts at 71 kg racing weight, my best 25 minute training interval of the year was 317 watts with typical hard 20 to 30 minute repeatable Threshold intervals in the 275 to 310 watt range.
Anyway you can look at the power profiling chart for comparison of weight scaled FTPs across a range of fitness levels but in the end you've got to set power targets for training based on what you can do and what fits your overall schedule. Read through the great info on the TrainingPeaks site and get a copy of Hunter and Coggan's book (or wait a month or two for the upcoming second edition).
Good luck,
-Dave