Wow, rock the fuck on. So we have a Blackjack already in the lance (I didn't think anyone would want that particular mech anyway) and I feel we should get another medium and two lights. I can happily provide advice on which light designs are particularly good, but I think a Raven or Ostscout is an excellent choice, as would be a Spider, a Locust or a Jenner if you want to go firepower heavy. Hermes is also a classic design. 

Or mediums, Cicadas, Sentinels, Phoenix Hawk -- particularly the latter as the command vehicle for a scout lance that itself is an effective scout as well. 

Pay attention to ECM and Beagle Probes, these are useful pieces of equipment.

I feel that the lance should be:
[indent]- Command: ([url=http://www.sarna.net/wiki/Phoenix_Hawk]Phoenix Hawk[/url] -- really recommended, upgraded variant like the PHX-1b which is the old Star League version and might well be field tested because of the re-discovered tech) 
- Fire Support: BJ-2X Blackjack. 
- Recon 1: ([url=http://www.sarna.net/wiki/Locust]Locust[/url] LCT-1Vb, -3S or -3D, [url=http://www.sarna.net/wiki/Raven]Raven[/url] -3L, [url=http://www.sarna.net/wiki/Jenner]Jenner[/url], [url=http://www.sarna.net/wiki/Cicada]Cicada[/url] -3M are really good examples, but there are other mechs as well in the light to medium category. You are allowed to play around and have custom configurations -- because it's a unit that field tests prototypes.)
- Recon 2:  (As above)[/indent]

The good news is this -- characters will not stay in these mechs for the duration if you decide to switch to other designs, because they will be made available in the course of the plot. You will get to go 'shopping.'