Why not just start out new nations with more mines or factories or cities? Hell give them 3 (?) cities to start with different specializations. So one for farms, one with factories, and one with mines. Maybe one with commerce. It may annoy more alliance trainers who have to hear "but I want to farm in my cities" but alliances have to train the bad habits out of dumb new players anyway. By giving a new nation a "taste" of each type, they have more things to play with, and have in their nations to control, more options. If you made it really advanced, and used different power plants in each city, and then included that in the tutorial (that people can skip, but mention it in the full tutorial) it would be even better at making sure new players actually have to interact with different aspects of the game. Interacting with something will teach someone (or at least make them aware of it) almost infinitely more likely than simply seeing in on the page if they are able to over look it.
The bias you take for the tutorial (what direction the tutorial makes them take to get the cash bonus, e.g. decomming farms and buying a stockpile of 400 per city from the market, or to go to coal mines and coal power plants, etc would be at the discretion of whoever is designing the new tutorial)
To not fully ignore the actual OP & poll, I feel the activity boost and all the other various new member bonuses may not be enough to fully give a player a taste of everything (my proposal), but this isn't doing much more than for example increasing the daily activity bonus. If they don't actually understand what's going on, or have to do anything to get it (such as, just signing in), they're not interacting and learning the game anyway. EDIT: To pile on to that last point, increasing the daily sign-in bonus at least makes them do something to earn it, rather than this current proposal. I think tying a resource bonus to daily activity would be a better fix than the current proposal. Still not my preferred option however.