Question - never had one in real or hobby life. Is it worth the effort? Two girls of course sounds great but grass tends to be greener with these things

Any comments are welcome

But, as with many things, the answer is, it depends.
By that I mean, it depends on where you find value and it depends on who you choose. If the girls have chemistry with each other and have often worked as doubles partners, you're more likely to have a good time.
I've done more than a few and, while I always enjoyed it, I prefer one-on-one.

If you have two girls just going through the motions for money, well that can be a drag. But if you can find two women truly into each other, while trying to satisfy your wants/desires, they can be incredible. If its on your bucket list, try it , but do your research first. Remember, your first one won't likely be your best. As it is true with virtually anything, the more experience you have will increase your enjoyment of it.

No contact at all with the other guy.. I find it very hot every time I have had this kind of 3some

With the right people, this is my favorite also. But I do enjoy a good sword fight.

I can't tell you whether it's worth it for you anymore than I can predict your taste in art.

I do think there are a couple of threshold criteria--
It depends on what you consider fun and making sure you set expectations.  For me if the 2 women aren't fucking each other silly with lips, tongues and toys, then it's a wasted session. You may be happy if they pay attention only to you. Either way you should be clear about what you want.  

It depends on whether the ladies are really into it. Whether they're supposed to fuck you or each other or both, if they're not 100% down with another naked woman within tongue distance, it's going to be an uncomfortable if not lame session. I've seen it happen where the two women were so ill at ease that they basically used me as a shield to avoid touching each other.  Not fun.

I’ve done a few and have a bi wife. Mainly get two women who are into it and like cock. Then your golden.

My favorite kind of threesome is 2 guys with Double Penetration (MFM) turns me on the most visually in pornography.