I think you would probably have to rely on mods to get what you want. Theres no way to make the AI challenging but not have them try to rapidly expand (without relying heavily on things like free building/unit rushing and massive economic bonuses). I can understand why you would want to build up your first city before doing anything else, I have the 'builder tendency' as well, building up cities and maximizing their potential is fun, but it just won't work the way this game is designed. Cities are power. The more cities you have, the more gold/research you can produce, you can build more units faster, you capture more resources, etc. Therefore it is a powerful strategy to go after land early, because if you don't settle it someone else will (this is the AI's logic, because the assumption is that the human player will settle it, so the AI has to be programmed to settle quickly or the human player will become too powerful), meaning you have gimped yourself long term. If the devs were to make AI expansion any slower than it already is the game would just be too easy, many players have already figured out how to expand faster than the AI even on the higher difficulties.
You might try fiddling with the game settings to see if you can get something closer to what you want. Put more AI's in the game than are suggested for that map size and put wildlands to max. This will still result in AI's quickly going for the few useable settlement locations, but it will mean all factions will be smaller in general than they usually are, and you will be at less of a disadvantage if you only settle one or two cities, or even just stick with only your capitol. You can also try setting the 'world difficulty' at its lowest setting, I believe this increases monster aggression towards AI players (I could be wrong on this), which might slow their expansion down.
In the end though, its a requirement that AI's be programmed to settle quickly if cities are to have any real purpose in the game. If cities are powerful, then players will naturally gravitate towards trying to settle as many as they can. If players are trying to settle quickly to get the most cities, then the AI has to try to combat this else it will never stand a chance. The only way disincentive-ize players from land grabbing is to make cities less powerful or to put heavy penalties on early expansion. I don't see Stardock going in this direction, but I can certainly see someone making a mod that does this.
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