I would absolutely agree about visiting Svens' site as linked above, however for discussion about all areas of spaceflight modeling you couldnt do better than to join the Yahoo group "Space Modelers" which caters for all levels of interest and is a great place to pose questions and search for previous posts on exactly the questions you ask.
When the groups files and photo sections are full Sven transfers them to his site.
Unfortunately in my opinion when it comes to Apollo space related "plastic models" the level of detail or accuracy has never been comparable to that which would have been deemed acceptable by the armour or aircraft enthusiast for example, many were tooled quickly in the 1960s to satisfy the wave of excitement during the "Space race" and based upon early representations or prototypes.
In 1/144 the two available Saturn v kits are the late 1960s tooled Airfix or Monogram (The Revell 1/144 kit is the Monogram) models which were remarkably similar and both had their plus and minus points.
Airfix has some rather nasty bulges on the seams and a few innacurate details which should be removed. The Revell Monogram is arguably the easier to paint due to the way parts are moulded.
Both kits had much too slim representations of the Command and service modules both as block 1 detail types.
As of late both 1/144 have been recently re-released, however Airfix have modified the Command and Service Modules to accurately represent a block 2 (as flown manned) to the correct size and this hugely improves the profile and overall look of the kit.
Revell released the Monogram kit in its original form but the decals were printed in black lettering instead of red.
Again only in my opinion, if you wish to build it straight out of the box the latest Airfix release would be your best option to achieve the most accurate result.
Ah, if only life and model rockets were that simple (I can generally cope with life).
To add to the confusion there are a number of companies which provide after market add ons to improve the results. RealSpace Models provides a corrected Command/Service module for the Revell Monogram and early Airfix 1/144 kits. NewWare Models provides extensive improved decal sets.
The Revell 1/96 Saturn V kit is again a model of its time the 1960s, built straight from the box it builds to an impressive model generally accurate in profile though not in flown detail. To me it looks as though it was based upon the NASA models of the time right down to the stand and could be seen in that light as a nostalgia piece.
Again using aftermarket parts great improvements can be made to represent a flight vehicle. NewWare can provide a super detail set and new decals. RealSpace sells a replacement Command/Service module and Boost protective cover which is not included.
The Revell kit uses plastic card wraps to represent the walls of the stages which are prone to relatively quickly yellowing and can become brittle especially in direct sunlight.
For further information on super detailing the 1/96 Saturn V Rich Sternbach has an excellent site.
The only problem here is you could end up not using most of the kit parts which rather defeats the object.
Quite recently a lovely small book came out called "Real Space Modeller, Volume One," which has some really nice builds of Saturn V models and may help you determine the level of detail would best suit you. There is also a very nice book by Mat Irvine called "Creating Space" which covers the history of space related models and lists virtually all kits available up until a few years ago.
The three main 1/144 shuttle stack kits are by Revell, Airfix and Minicraft which is the same as the old Entex kit.
The nose on the Minicraft Shuttle has an inaccurate profile which stares out at you but otherwise I think is a quite nice model.
The Revell Germany and Airfix later releases both have excellent much improved decal sheets and personally I like the Airfix kit fit though the External tank requires corrugations which are on the Revell kit. Both can be made into really nice models but do benefit from replacement Main engine nozzles which are available.
There are so many variables with the shuttle depending whether you wish to build it as a pristine looking generic representation or if you want to build a mission specific weathered model. Space in Miniature offers information on detailing the space shuttles.
Jay Chladek has some great kit reviews on YouTube these include the history of shuttle kits.
I'm sure someone said this was meant to be fun.