>>7189291This or the Hydronauts base were what I wanted as a kid, but only ever got the little grocery store sets, like the Solo Sub and Sea Sprint 9. Fort Legorado, the Fright Knights castle (6097), and the different Ninja buildings (3053, 6093, etc.) were all wants of mine. My parents did fuck up and got me the Mega Blocks Planetoids LX-009 City one year for Christmas, but when I moved and had to give toys away, that was one to go.
Objectively the best building sets right now might be Ninjago City and Ninjago City Docks, plus The Old Fishing Store. But they're not "bases" or "HQs." Subjectively I'd like Garmadon's Volcano Lair or the Sanctum Sanctorum Showdown.
>>7189638That one is better than The LEGO Ideas Book, imo. You might want to look into third party books, too, like The Art of LEGO Design by Jordan Schwartz and The LEGO Neighborhood Book by Brian Lyles. Some of the individual themed books like the Star Wars ideas book are just okay, but from flipping through there were a lot of alternate builds or recolours of sets. Note: I have yet to borrow The LEGO Play Book and 365 Things To Do With LEGO Bricks.