My main add-ons to affect the appearance of my FS 2004 Scenery:
Payware FS Global Scenery SE Mesh....(one of the first to install, long ago!)
Freeware scenery meshes and land-class for local areas: (Sim V Library).
Freeware VOZ 1.8 for scenery colours, and the free, gorgeous "Koorbygen" buildings!.
Payware REX for various textures.
Gerrish Grey's free tree sets, (for my lovely, golden, Autumn trees!).
And that's about the lot, together with careful selection of
location, month, time of day, and default weather.
LAGO FSE; "Flight Sim Enhancer" gives me the opportunity to add various objects; HUMANS!, aircraft, buildings, etc, etc, to make my ground scenery come alive, in FS 2002 and FS 2004!..(you don't get that for FSX!)
(...and most very recent, days ago, for the USA: Ultimate Terrain USA and Canada, to show real roads, rivers, railways, coast lines, etc, for my explorations!).
All my FS 2004 settings, sliders, etc, are set at maximum, which my lowly computer hardware allows, (P4 Dual Core 2.8 GHz/n-Vidia GF 9500GT 1 GB), with little, or no effect on frame rates. Locked at 20-25 FPS. (You cant do that with FSX!)
FS 2004 contains everything I need for my particular purpose...which is wonderful....

...!
Paul....

...!
Oh...and I mustn't forget, the most important thing of all....FS Navigator for flight planning and Multiplayer Radar!...(You don't get that for FSX!).
Win 8.1 64-bit. DX11. Advent Tower. Intel i7-3770 3.9 GHz 8-core. 8 GB System RAM. AMD Radeon HD 7700 1GB RAM. DVD ROM. 2 Terra Byte SATA Hard Drive. Philips 17" LCD Monitor. Saitek Cyborg X Fly-5 Joystick. ...and a Briggs and Stratton Petrol Lawn Mower.