even on grand admiral stratedy to win is usually the same.
tall or wide doesn't matter as long as your economy\fleet(cap and actual built ships)\science constantly grow.
in my recent games I prefer semi-tall with slavery - conquer enemy and you have a lot of free pops to build more buildings on every planet(especially if you've reached ecumenopolis). though you need few food and mineral planets to work. start with 5 science ships and map the stars to get a lot of anomalies (research them later) with luck it may give you free ships or resources. colonize nearby planets(at least 1) ASAP. then focus on science and fleet(I tend to go for twice the fleet cap early game - it's like 3-4 full corvette fleets). if you have a neighbor nearby - kill it asap(before 2220 or he may become too strong) to start snowballing, otherwise try to be as peaceful and friendly as possible . as for ship designs - missiles suck. so either a mix of kinetic and lasers or full disruptors. build Destrs only for PD. and skil cruisers entirely
on default galaxy settings my milestones are year 2270-2300 - leviathan hunting, 2320-2350 - killing khan. year 2350-2400 - killing all FE\AE then 2400+ crisis wars. after that build colossus for an easy total war against everyone (you don't have to use it. only to build to unlock the war type)