Hopefully this isn't a duplicate idea, but I don't see a good method on the site to search through existing posts. I did look around a little bit and didn't see anything that was obviously the same as what I am about to propose. (Maybe better searching/navigation for the posts would help with this?)
At any rate, I enjoy the research aspect of the game. I would love to see a huge increase in the number of available technologies to research. The concern that I have with making the tree significantly larger though is that it would be impractical to make use of much of it in practice due to the limitation of researching a single technology at a time regardless of how many research stations you have.
For the most part, I think the existing techs are reasonably priced in terms of tier, price, and time. What I propose is the following:
Researching a tech requires an available number of research stations/labs (off planet or on planet) equal to the tier of the technology just like the game does today. However, when you choose to research a tech, it only uses the number of research stations of that techs tier. If you have more, then the "idle" ones are still available to use to research a tech up to the tier level of how many are still available.
In other words, if you have 5 research buildings/labs you can research 5 tier 1 technologies at the same time, or you can research 1 tier 4 tech and one tier 1 tech. Or you can research 1 tier 3 and 1 tier 2 at the same time or any other combination of technologies where the total sum of the tiers being researched in parallel does not exceed your total research tier.
Some people might suggest that if you have more labs than are needed for the tech, that the extra labs result in the research time of the tech decreasing. I'd be open to trying that out as well, but I think that would affect the strategy in a different way than the parallel research proposal. I think it would be more interesting from a strategy standpoint to have to make a decision between using all labs to research a single high tier tech, or allocate them to researching multiple lower tier techs concurrently, while not being able to change the time required to aquire any single tech once you start researching it.