Welcome to the Community,
whether to resize or create new virtual disks depends on your individual needs. Basically I think it's way easier to resize the existing virtual disks to avoid the need to split data and keep free disk space on 3 disks (i.e. wasting disk space). You can have virtual disks with up to ~2TB (2,032GB if you want to be able to use snapshots) provided you either use VMFS5 datastores or vmfs3 datastores with an 8MB block size.
With that said, you may also need to consider backup&restore. Depending on your SLA's you may need to have think of restore times, which will certainly grow with the disk sizes.
André