series parallel wiring 8 ohm speakers

I am trying to wrap my mind around this...and all the research has given me two very different results, so I come to the experts here.

Due to the shape of my under construction dedicated theater room, I need to put two side speakers on each side wall (well, only one side needs it, by symmetry demands both get it then), all speakers are 8ohm. Basic research says to wire them in parallel, making them appear to be one big 4ohm speaker.

All well and good, as long as I make sure my AVR can handle 4 ohm speakers...but is there some hidden problem I need to look out for with this?

Also, assume I want to wire three speakers together onto one amp. I would have a load of less then 3ohms impedence, which is bad. Could I wire them in a series-parallel configuration to get 6ohms? It would be two in parallel, then that parallel in series with the third...so 4 ohms for the parallel and 8 ohms for the series makes a very large 6 ohm speaker.

Any pitfalls with that setup? Only asking because I have been slowly upgrading my speaker setup and may find myself with a spare Paradigm Millenium Trio 20. It is a speaker bar, basically, and has three sets of 8 ohm speakers all connected together. It could make for a very large center channel.

So using the two speakers in Parallel (for a 4ohm load) would be fine, but not the strange series/parallel setup I mentioned?

I will most likely just use the outer two speakers of the Trio in parallel then to make it easy and cheaper. Basically as a wider, center channel.

EDIT: Although it might not be bad to have the load slightly strange if the center speaker was the higher volume and the two outsides were the lower volumes...

I just did a test and my AVR can run the outer two speakers on the Millenium 20 Trio off the center channel, wired in parallel. This has greatly improved my center channel's impact, wife is happy.