For the sake of discussion, I looked at the Apollo numbers as a starting point:

(Weights are not typical for every mission)

LAUNCH ESCAPE TOWER
Overall length: 10.2 m
Diameter: 0.66 m
Total mass: 4,173 kg

COMMAND MODULE
Crew size: 3
Length: 3.5 m
Maximum diameter: 3.9 m
Habitable volume: 6.17 m3
Total mass: 5,806 kg
- structure 1,567 kg
- heat shield 848 kg
- reaction control system 400 kg
- recovery equipment 245 kg
- navigation equipment 505 kg
- telemetry equipment 200 kg
- electrical equipment 700 kg
- communications systems 100 kg
- crew seats & provisions 550 kg
- crew mass 216 kg
- misc contingency 200 kg
- environmental control system 200 kg
- propellant 75 kg

We'd need a bigger capsule if you wanted to carry more people on a regular basis. I believe the mass of that increase could be offset by newer materials. Here's a WAG based on newer technology and simplier mission requirements.

- structure 1,567 kg
- heat shield 500 kg (Note 1)
- reaction control system 400 kg
- recovery equipment 245 kg
- navigation equipment 100 kg (Note 2)
- telemetry equipment 100 kg (Note 3)
- electrical equipment 400 kg (Note 3)
- communications systems 40 kg (Note 3)
- crew seats & provisions 550 kg (Note 4)
- crew mass 420 kg (Note 5)
- misc contingency 200 kg
- environmental control system 200 kg
- propellant 75 kg

Estimated mass of the capsule: 4797 kg, a savings of almost 18%. As a WAG, I reduced the mass of the launch escape system by 18% to get 3422 kg. That puts the mass of the capsule and escape tower at 8219 kg.

Next, we'd need to develop an orbital maneuvering system capable of providing the rendevous and deorbit capability. Depending on the amount of maneuvering necessary, this should be possible with a service module of 4000 to 10,000 kg.

Unless you're planning on flying the GEO and polar missions only from French Guinea, I don't think an Ariane V has the lift capability necessary to lift a service module with enough propellant to circularize the geostationary transfer orbit, rendevous with something, then reduce velocity enough to return to Earth. For that kind of mission, I'd rather see a very small vehicle like an updated Gemini capsule. Even with only two people on board, the amount of propellant to circularize at GEO is substancial, as is the amount necessary to come back down. This capsule would be too heavy for that flight profile.

Note 1: The Apollo heat shield was designed for a return from the moon, which involved about twice the energy of a return from Earth orbit. Between slower reentry speeds and new technology, I believe this estimate is, if anything, on the high side.

Note 2: Apollo's navigation equipment was based on a heavy flight computer and the need to fly to and from the moon. Simplier mission requirements and newer technology should mean this equipment will be much lighter.

Note 3: Estimated mass due to newer technology, especially in batteries and electronics.

Note 4: I left this one alone even though there will be more seats. It might need to be increased but perhaps not by much.

Note 5: Allowed for 70 KG per person times 7 people. Give or take.