Re: Glenlivet 12
Many distilleries have a "bog standard" official bottling. these are usually "nice" and "drinkable" and I certainly wouldn't say no to any of them if offered.
All quality whiskies that are enjoyable. Glenlivet 12, Glenfidich 12, Glenmo standard, GlenMoray, Macallan Fine Oak 10 etc. Certainly some more than others may be worthy of "diving deeper in the glass."
But all have more esoteric bottlings. The jump to the Glenlivet Nadurra from the 12 is quite large. From 40 to 48, or 57% depending which version; a lack of filtration; Much more intensity and focus in nose and flavour...
Actually, it would work well in one session. Start with the 12, and let your refill be Nadurra!
Very different whisky experiences, that's all.