Looking outside the Traveller canon, the ruleset "Strike Legion: Planetary Operations" by Legionnaire Games is excellent for resolving those planetary invasion type big battles. Not Traveller but can be Traveller-ised successfully.
For engagements up to a company I tend to use Steven Madjanovich's Striker-ised version of MegaTrav (http://webcache.googleusercontent.c...om/rpg/basicinf.asc+&cd=1&hl=en&ct=clnk&gl=nz) in preference to Ref's Companion. It has less quirks, and requires A LOT less book-keeping than Ref's Companion combat does.
For engagements up to a company I tend to use Steven Madjanovich's Striker-ised version of MegaTrav (http://webcache.googleusercontent.c...om/rpg/basicinf.asc+&cd=1&hl=en&ct=clnk&gl=nz) in preference to Ref's Companion. It has less quirks, and requires A LOT less book-keeping than Ref's Companion combat does.
