I wouldn't worry about corridor noise. These days, unless a couple of passengers are 'getting loud' in the hallway, you won't hear them. Having quick access to the coffee can be beneficial. As for the shower 'crowd', I rarely see used towels in the bag in the shower when I wander down the hallway to shower when I get up. So there won't be any door banging, etc. Only once in the 20+ years the Viewliners have been rolling have I had to move someones' giant sized luggage out of the shower so I could use it. But 2 or 3 times, I've had to move the Amtrak-special 'giant trash bag' out of the shower...all in the past 4-5 years. I make it a point to NOT ride in the Boston section sleeper on 448/449 as it's up front and too much horn noise. Since discontinuing the Boston baggage car, it's the first car behind the locomotive(s) and sleeper passengers get their giant luggage 'checked' on the sleeper. Spare roomette? Doubtful. Shower? Sure thing, I suspect. But then, this summer, there's NO Boston sleeper and it's now the 3rd New York sleeper at the rear due to CSX trackwork on the line and 448/449 is a train only 2 days per week.
My only complaint about roomette #11 is the somewhat rougher ride due to proximity to the trucks. I've caught #11 or #12 a couple of times through the years. I'd willingly ride in either room again.
Is it possible to call and get a different room? If there's more than one sleeper on the train, there may be a lower-numbered roomette in the other car(s) or even the same car due to cancellations. But be warned...modifying your reservation gets current-pricing, which may be either higher or lower than what you paid. Don't be surprised if they want another $100 to switch rooms as prices escalate closer to departure date.