AIX 5.x and VERITAS VxVM works fine for me, existing VG's can be converted into VxVM Disk Groups. Beeing used to how it works on Solaris it is good to use the same sort of storage administration on AIX. Some nice features: striped-mirrored and mirrored-striped volumes, dynamic volume re-layout, shrinking/growing volumes along with the filesystems on the fly, software RAID5, volume replication (additional license for Volume Replicator neccessary), fully integrated in smit/smitty, device discovery layer with full array and multipath detection, etc, etc ... I used to like the AIX LVM but the VxVM would definitely be my first choice now..
/vxman