I'd like to suggest that the larger missile launchers have to be researched.
Maybe make 1-25 low tech, and 25-50 cost 1000 each, then 50-100 cost 2000 each.
Also take launcher max size up to 1000, in increments of 50 between 100-500 (i.e. 150, 200, 250, 300, 350, etc.) and 100 between 500-1000 (i.e. 600, 700, 800, 900, 1000) 1000 size box launchers shooting ship sized torpedoes to blow up entire planets/fleets is fun. (I made a 1000 size MIRV that broke up into thousands of small deadly dart missiles with their own targeting software)
Also how about higher jump drive efficiencies? i.e. 30, 35, 40, 45, 50 etc. Doubling the RP cost though would make it go too high though, so maybe stick with a 10% increase in the cost? Max jump drive already costs a lot so it would still take a while to research.
Also, maybe you could play a game with some giant big ships. There are some problems with them (Sensor Errors, Fleet Contact Errors, Maintenance error overflows, extremely long time to load fire-control systems (Because of the sheer number of weapon systems. Maybe once the list gets so large group the weapons into tens so each weapon represents 10 of the guns on board?)
Also a larger fuel tanks/crew quarters/engineering spaces would be nice. (156 thousand engineering spaces on my 50 million ton super monitor took a lot of x100 clicking...only to throw a maintenance error every cycle that results in no maintenance failures! Might as well not put any on there!)
Of course you might of already fixed this for 4.9...I just upgraded and it will take some time to rebuild. (In fact I never managed to actually build a ship larger than 6 million tons, the 50 million monitor was fast OBed in to test it out on my playground game

)
Edit: Also, can we have a button to add a shipping line that isn't Spacemaster, that costs an amount of wealth (Maybe 5-10% of your total wealth?)