I find that road/highway connections don't always kill your MT connections. In my current region, I have a central city of about 200k that started as a industry city only, surrounded by 7 cities of limited population (due to land availibility), and 1 large city tile with I-HT jobs and CS jobs, to use up my CS demand (havent put a dent in it and I have 20k+ CS$ and CS$$ jobs). I recently connected all cities with a bus/subway thanks to the NAM's road-top transit, and the number of commuters going from the city center to the suburbs and I-HT areas is about 20k car, 10k bus, 11k subway. The traffic volume chart showed a drop of at least 100k in car usage when I built the intra-city subway, and another 20k when I built the inter-city network. The center city is still the main supplier of jobs in the region (400k I+C). The reasons for this could be that my connections are very limited (highway between any city with population+jobs>25k, avenue 10k>p+j>25k, and road if p+j<10k), and the highways and avenues are all extremly limited access, while the MT has a stop at every intersection. On the water topic, make sure you have at least 10k m^3 excess capacity, more as your city grows in to stage 6+. I forgot to have lots of excess capactiy in my city and the main city stopped buying all water, forcing me to revert to a saved game. (When you're selling 250k m^3 of water a month, it is a considerable part of your budget.)\ Good luck with your city, and unless your really strapped for cash, toll booths are generally a bad idea, but its your city.
