Been following this thread and also the other one about gearlevers, got a couple of suggestions that may help with the ultimate diagnosis of the selection problems that seem to be fairly common judging by the comments in general!
First of all, check there are no mats, carpets etc that could interfere with fully depressing the clutch pedal. The original carpets are fine but any more than that and you need to remove them, even if only for the duration of testing just to be sure.
If coming to a stop or trying to select a lower gear to go round a junction or similar, depress the clutch, move to 3rd then swiftly into 2nd and then 1st if wanted. Don't let the clutch up while doing this and make each change as quick as possible.
Likewise if idling see if selecting 3rd then 2nd and finally 1st with the clutch fully depressed makes life easier.
If so, try bleeding the clutch hydraulics. If this still doesn't improve matters then it's either a selection problem within the box or the clutch is dragging.
This would almost certainly be due to a weak/worn pressure plate/cover which can be verified by switching the engine OFF, depressing the clutch and selecting all gears.
If any difficulty is encountered then it's a selection problem in the box although you may have to go 4th, 3rd, 2nd, 1st the first time just to align the synchro hubs. Also is reverse difficult to engage from idle? If so, this also points to a dragging clutch.
A final point about gearbox oil - when was it last changed? Sometimes fresh oil is enough to overcome any clutch drag if it's not too severe. However it can make selection of all gears copmaratively stiffer from cold but this usually disappears fairly quickly.
Something to remember is that most of you haven't owned the cars from new and have no idea how the previous owner treated the clutch - they could have rested their foot on it while driving, commonly called "riding the clutch". This causes extra wear on both the release (thrust) bearing and also the pressure plate, weakening it.
Good luck with reaching your conclusions and i'll keep following this.
