an easy way to use decursive is just make a macro that's /decursive and put it in an easy to reach hotkey.
as far as UI mods I use:
titan panel (I just like the update on gold earned/lost and durability since I have to switch gear every now and then, and the system info)
scrolling combat text (still better than blizzard's, if only due to the awesome fonts)
decursive (even though I'm a warlock main, I use it on my shaman alt and other alts I've played)
countdoom (a way outdated warlock addon, but it doesn't screw up to load it out of date... and it provides much more accurate timers for dots/curses/enslave than necrosis, without all the extra garbage in that largely overrated mod)
lootlink
auctioneer and enhanced item tooltips
itemrack
tauntbuddy
ctmod and ctraid
la vendetta boss mods (WAY superior to ctraid, I just recently discovered it though)
honestly, I use too many mods and I should probably just delete my interface folder and start over again. I should get discord or nurfed ui, but I tried discord and it was a bit annoying having to rebind every key and then spend time to reorganize and redo my entire interface. I'll still get to it eventually, though, cause blizzard's default UI is getting outdated quickly.