I am using AOS v 5.0.0 or 5.0.2 (don't remember which) with an ATI Radeon X600 in dual head 3840 x 1080 resolution on an ASUS motherboard with an AMD processor. Win-OS2 works in all modes: full screen, Win-os2 session, and seamless, although it took a little adjustment to get the seamless to start without a dialog box popping up.
I also have a Lenovo laptop with Intel core 3 running AOS where Win-OS2 does not work in any form. (Except I tried one of the unofficial fixes from AOS specific to another user and got it working for a few hours and then it stopped.)
Essential utilities: I install Win32s 1.3 and then back-install Win32s 1.25a to get a couple programs that "require" win32s 1.3 to run - one of those being FrameMaker 5.5. The other utility I use is WinZombe to completely terminate seamless sessions that won't close properly. (I promised Martin to open source that and then decided to rewrite it so I wouldn't be embarassed and then got distracted before finishing, but I will finish it and send it to you Martin.)
Programs: I use FrameMaker 5.1.1 on a regular basis because I am used to the program and there are some things it does (create a PDF with hyperlinks in the document) that I don't believe are available on an OS/2 program. I also use Lotus Improv v 2 which was never ported to a 32 bit version and is fantastic, ReportSmith v 2.5 (I cannot get v 3.0 to run in ODIN) for creating printed reports from a database, and Q+E/Intersolv database editor for viewing and editing data in databases. There was a version of Q+E database editor for OS/2 and it still works but it was released before Q+E switched to using ODBC drivers and so it only works with the databases that Q+E wrote their own interfaces for, so I have to use the Win-OS2 versions to get at other databases.
Documentation for tuning: The best I have found is RedBooks GG24-3731-00 "OS/2 Version 2.0, Volume 2: DOS and Windows Environment. It is part of a 5 volume series that came out with OS/2 version 2 explaining how the operating system works. (GG24-3730-00 Volume 1 Control Program, GG24-3732-00 volume 3 Presentation Manager and Workplace Shell, GG24-3774-01 volume 4 Writing Appplications, GG24-3775-00 volume 5 Print Subsystem)
I have tried DosBox on the laptop as a WIn-OS2 substitute and sometimes Improv works and sometimes it does not. The work-around that always works on the laptop for me is Improv running in Windows XP running in VBOX.
Reason why Win-OS2 is important: 1) applications. There are some Win16 programs that I use that were never ported, and some Win16 programs I use that have no OS/2 equivilent. 2) money, I have tens of thousands of dollars I have spent on software that I don't want to spend again even if there is a new version available.