I always "request climb to VFR on top"
That gets up above the low fog/overcast that is a problem for most VFR pilots to go anywhere significant, and is common in summertime mornings around my area.
It is an IFR clearance, and it is given with something like:
"if not VFR by 4000, report"
For my local field the clearance is usually published procedure, then direct to a local VOR about 15miles away. By the time I report in the air, usually get a vector, and am on top shortly. Of course, VFR means 1000' over the layer. So when I report on top, and either continue flight following services, or cancel if going to a local field, I'll give the base and top layers as a report, since this kinda popup is quite common in my area.
As far as VFR while on an IFR plan, I'd prefer to NOT do that. Keep me that extra 500' from other VFR traffic out there that may be along or passing over the airway I'm on, thank you very much
Josh