If I found the right place, it looks like a long walk with suitcases. I see Clinton that is in the northwest corner. Am I looking at the right one?
It's about a 2 and 1/2 block walk from the Clinton Blue line station to Amtrak's Union Station. One enters the Amtrak station on Clinton and walks through the old main waiting room, to reach the new waiting rooms.
As for the Blue line trains running slowly that other's have mentioned, the CTA as noted by Robert Madison in a topic in the special forum for the gathering, is currently undertaking the needed repairs to fix the problems and allow the trains to run at normal speeds. This work should most likely be done long before you'd be using this line, next summer.
It depends on which "work" we're talking about. The whole Blue Line Slow Zone Elimination Project (whether or not it has an official name, I don't know), will run through the end of next year. The work is being done in phases. Phase I was just completed, with the slow zones between Grand and Division in the Milwaukee Avenue subway being lifted this past week.
The next phase is Jefferson Park to Harlem, as I noted in another post (in the gathering forum, see my note to folks staying near O'Hare), which should run October to early December. The third phase, which starts next spring, is a varying zone between Jefferson Park and O'Hare (mostly west of Harlem, though). The fourth phase, between Jefferson Park and Belmont, will be next summer through the end of the year.
If you're traveling during a weekday, during daytime hours, you shouldn't see much impact. The trains may be slow in sections (but they're slow now), but service will be running at what passes for normal. If you're traveling during a weekend (or overnight), there is a possibility that the line may be cut and replaced with shuttle buses. Depending on the exact work being done at the time, that could significantly increase your trip times, or only have minor impact.
If you have any questions, let me know as your travel date gets closer, and hopefully I'll have better details on what to expect.