Third-person is the most 'acceptable' way to go, which means having to use attributions like 'Bill said', 'Monica said'. Or thought.
A lot depends on the size of the blocks of POV. If you want to quickly switch between points of view then third-person will do it. For longer passages with a character, you should use individual scenes as natural section breaks.
The italics could work for rapid character switching, but I'd use it sparingly unless you want to make the format a deliberate and obvious gimmick for your story. I think that generally, 'head hopping' is frowned down on, particularly if it's spammed.
Interestingly, I've just remembered Dickens's Bleak House, most of which is written in third-person but where there are whole sections written as first-person specifically for Esther Summerson's point of view. It goes to show there's room to improvise with this.
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