Zaandam - Why such variance in the size of Vista Suite

We are looking at booking a cruise on the Zaandam. In looking at the specs for the cabins on some of the web sites it looks like the Vista Suite sizes have a huge variance (from 297 sq ft to 379 sq ft). Is this correct, and if so, how does one find the larger cabin sizes?

The cruise that we are looking at has a promotional offer for suite customers of three nights post-cruise in Buenos Aires. Are there any other on-board perks that come with booking a suite?

I only took a quick glance at the deck plans. It appears that the larger Vista suites would be the handicap accessible suites. The rest of them all look equal in size to me.

You'll get the use of a telephone concierge in a Vista Suite.