Teh Final Loadout
Here is the set of plasmids and tonics I used in much of the endgame.
Telekinesis, Electro Bolt 3, Target Dummy, Insect Swarm 3, and Hypnotize Big Daddy 2 served as quite the versatile arsenal. I found Target Dummy to be especially useful late game to lure splicers into traps and to get around turrets. At a certain point leading to the final encounter, I kind of knew I wouldn't need Hypnotize, but it kinda became like a good luck charm.
Also to note, nothing fancy in my ultimate Combat Tonic selection. As I had maxed every type of Splicer or Daddy in regard to Photographic Research, stacked Research Damage 1 and 2 increased bonus damage 90%. Likewise Armored Shell 1 and 2 for overall defense.
As you can see I didn't go crazy on buying additional plasmid and tonic slots. I did buy every available Health and Eve upgrade, though, as far I could tell.