I reckon you have four distinct options
Option 1 is the most expensive
Main Building
1 x Superstack 3 4400 48 port 3c17204
1 x 1000BASE-SX module 3c17221
1 x 1000BASE-TX module 3c17220
Second building
2 x Superstack 3 4400 48 port 3c17204 or 1 x Superstack 3 4400 48 port 3c17204 and 1 x Superstack 3 4400 24 port 3c17203
1 x 1000BASE-SX module 3c17221
1 x 1000BASE-TX module 3c17220
1 x Stacking Kit 3c17227
The second building has a stack of two switches one has the 1000BASE-SX uplink to the main building and one has the 1000BASE-T uplink to the main building. Only one will be in use at a time since spanning tree will block it and Link Aggregation does not cross modules.
Option 2 is as option 1 less the stacking kit.
An alternative scenario is to not stack the switches in building 2 just leave them with a connection each to the switch in the main building, this makes sense as all the shared services appear to be off the switch in the main building. In this scenario two or four ports can be aggregated to interconnect the switches in building two and used to create a resilient link.
option 3 uses 3300s in building 2 rather than 4400s
Main Building
1 x Superstack 3 4400 48 port 3c17204
1 x 1000BASE-SX module 3c17221
1 x 1000BASE-TX module 3c17220
building 2
1 x Superstack 3 3300 SM
1 x Superstack 3 3300 MM
1 x Superstack 3 3300 TM
This creates a stack with an SX port and a 1000BASE-T port
Option 4 has a 3300 stack in each location
Main Building
1 x Superstack 3 3300 SM
1 x Superstack 3 3300 TM
building 2
1 x Superstack 3 3300 SM
1 x Superstack 3 3300 MM
1 x Superstack 3 3300 TM
This is the cheapest option but potentially the one with the most bottlenecks, particularly the 3300 stack in the main building.
At the end of the day you pays your money and make your choice. When I calculated the cost of the options there was just over a £1000 difference in cost between option 1 and option 4 and less than £300 between the two if building 2 uses 1 x SS3 4400 48 port and 1 x SS3 4400 24 port. The difference would be negligible if one takes into account the added features of the 4400 over the 3300 and extra power of the switches.
I hope this helps.