Awesome. Yeah, that is probably for the best. Generally speaking, I say keep it simple. Not saying saying to not use different OSPF areas, but the most common reason folks do that is to summarize.
Let's say your data-center site has 10.0.0.0/24, 10.0.1.0/24, 10.0.2.0/24, and 10.0.3.0/24.
You could summarize to /22 which would take those four /24 networks and present them as one /22.
Ordinary, it would announce itself to other areas and appear something like this:TEST#show ip route
10.0.0.0/24 is subnetted, 4 subnets
O E2 10.0.2.0 [110/20] via 192.168.12.1, 00:00:20, GigabitEthernet0/0/0
O E2 10.0.3.0 [110/20] via 192.168.12.1, 00:00:21, GigabitEthernet0/0/0
O E2 10.0.0.0 [110/20] via 192.168.12.1, 00:00:22, GigabitEthernet0/0/0
O E2 10.0.1.0 [110/20] via 192.168.12.1, 00:00:24, GigabitEthernet0/0/0
Tell it to summarize to /22 by pasting something like this into the routing process:summary-address 10.0.0.0 255.255.252.0
Results:TEST#show ip route
10.0.0.0/22 is subnetted, 1 subnets
O E2 10.0.0.0 [110/20] via 192.168.12.1, 00:02:06, GigabitEthernet0/0/0
I hope that helps. It would summarize between areas. What is important is that you have an Area 0 as your backbone and every other area connects back to the backbone. Hence if routing from Area 1 to Area 2, data would travel from Area 1 through Area 0 then to Area 2. From there you would chop up "contiguous" subsets and assign them for use in each area to allow you to summarize.
In the above example, 10.0.4.0/24 would be listed as the next /22, but
you would have to also add:summary-address 10.0.4.0 255.255.252.0
Results:TEST#show ip route
10.0.0.0/22 is subnetted, 2 subnets
O E2 10.0.0.0 [110/20] via 192.168.12.1, 00:02:06, GigabitEthernet0/0/0
O E2 10.0.4.0 [110/20] via 192.168.12.1, 00:01:01, GigabitEthernet0/0/0
However if you summarized to /21 you would be covered through 10.0.0.0 - 10.0.7.255...
Example:summary-address 10.0.0.0 255.255.248.0
Results:TEST#show ip route
10.0.0.0/21 is subnetted, 1 subnets
O E2 10.0.0.0 [110/20] via 192.168.12.1, 00:02:06, GigabitEthernet0/0/0
Hope this helps... With four sites, I probably would not bother summarizing especially if the subnets are not contiguously assigned already unless you want to re-work your subnets. IF you are assigning different areas, it is my sincere recommendation to keep contiguous subnets together for use in each area, so in the future if someone does want to summarize (i.e. as the network grows) it will be easy. In the above example, you would not want 10.0.0.0/24 and 10.0.2.0/24 in one of your areas and 10.0.1.0/24 in another area. Hope the above helps.