Denise & Alan - Have a great trip :)
We've been on two river cruises (the Danube in 2005 on Avalon and in July on the Rhone/Saone on Uniworld).
We had the top category cabin (not a suite though) on both with the "french balcony". Since very little time is spent in the cabin on these river cruises (compared to Regent etc), I don't think there is a big benefit to a "full balcony" (which may cause the rest of the already fairly small cabin to be smaller - perhaps Ngaire can comment on the feel of the cabin between Amadeus & Scenic). Also, the way that these river cruises work, when you are docked (usually during the day), several boats are usually stacked up against each other (you walk through the lobby area of other boats to get to the dock), so you wouldn't want to sit out on your balcony anyways since you'd just be looking directly into the next boat's cabin. It is nearly impossible to make sure that this doesn't happen to you even if the line "pays extra" to be the boat right next to the dock since there doesn't seem to be a consistent way that they dock - starboard or port. Even if you're right next to the dock, the full balcony would put you at the same level as the dock basically.
I think that a "french balcony" is fine especially on deck 3. Most of the newer boats also have these on deck 2 (but the savings is minimal). However, I would not accept a cabin on deck 1 with portholes/windows since you could feel submerged under water at times.