Not sure what to do ????

We are about to get Natural Gas. We have cast iron radiators and we need to have hot water for the shower and wash dishes etc. etc.
So should I get a Natural Gas Boiler and a natural gas water heater ? We presently have an Oil Burner Boiler with a tankless Coil(that heats the hot water). My Wife is not happy with the Coil in the boiler because there is not enough hot water. We need more hot water and not intermittent hot water etc. Do they have boilers that will provide heat for the cast iron radiators and a "ton" of hot water ? Or do I need a separate Natural Gas Hot Water Heater in addition to the Natural Gas Boiler ? Or do I need one of those boxes on the wall that heats the house and I believe provides hot water for showers etc. ?

Thank you

Best set up we ever had was a Buderus natural gas boiler with indirect hot water. The indirect is a 50 gallon storage tank that connects to the boiler through a heating loop, in other words the boiler heats the hot water just like the radiators, by circulating hot water through a coil in the storage tank. Raised two girls in that Long Island house and we could be washing clothes, running the dishwasher and have both showers going all at the same time and never ran out of HW. Two zones of hydronic baseboard in that house.

Our other house on LI had cast iron radiators and when we converted from oil to gas, we installed a Bosch Combi that has an on-demand water heater built in to the boiler. Supposed to be very efficient and can keep up with demand much better than the old boiler coils. It worked great, but not many sold here, only one dealer would install the unit and he knew zero about fixing it. Thankfully we never needed service, we sold the house 5 years later.

You could always go with a stand alone gas HW heater, but also requires its own gas connection and venting.

why not just stay with oil?
a nice weil mclain oil fired boiler with a tankless?

We're on electric here in IN, but for a long time natural gas was much cheaper than oil and it likely still is. High efficiency boilers use PVC exhaust, no need for a chimney. We freed up a lot of space in out 1917 house on LI ber removing the chimney. Plus constant supply vs. deliveries. Friends on LI has auto-delivery of fuel oil and went to FL for January one year. Oil company missed the delivery, tank went dry, pipes froze, huge mess with whole-house soaking. Neighbor called them in FL to say there was a waterfall coming down the front stoop.