Happy to help!
Another map type I'd mention is X; on some X maps, you can fit in 5 Cities in one of the four 'branches', and put everything into a single chokepoint. But 80-Planet X maps which have that may take some time to find. Again, make sure any standing AI worlds behind your chokepoint don't have any structures with full warp gate functions, or you may find a massive exogalactic strikeforce in your back yard.
On a spire-heavy campaign, I often play on a 90+ planet map, and take two or sometimes three homeworlds, because this usually makes Spire logistics easier. Though if you start with multiple homeworlds, take care with choosing their locations, otherwise you might screw up an optimal placement of Spire Cities.