There are at least as many answers to the original question as there are types of rifles to be used in the field. This is confused by the fact that many "peep" sights can also be "ghost rings" . Another interesting complication is the manner in which the rifles are constructed - that is to say that not all SxS doubles are made the same. The same goes for bolt actions, lever actions, and single shots. Whether a custom rifle or a factory rifle also complicates matters. The telescopic sight adds another level of complexity to available options. And possibly the most important is the shooters capability with one or more types of sight. Then you add in the type terrain and type of game to be hunted and the puzzle is even more interesting. Here are some that worked for my rifles in the USA and Africa.
1. Scoped .308 Winchester M70 for all plains game in Africa and USA
2. Scoped Ruger 77 .338 Win Mag Africa and USA all plains game
3. USA truck gun Custom Winchester M92 .357 Magnum with receiver peep, 20 inch barrel
4. Winchester 1895 .405 WCF with extended chamber, 210-400 grain bullets, receiver peep, 24 inch bbl,
USA and Africa all plains game and large and dangerous game.
5. Winchester 1886 TD .45-90 (.458 2.4) with 26 inch BBL, with tang peep and flip up barrel sight, all USA and Africa plains game + Bison, elephant, Cape Buff, leopard. 450 grain solids at 2150 fps.
6. Beretta .45-70 DR for USA plains game
7. Simson and Co Suhl .405 WCF DR regulating 300 and 400 grain bullets-for USA and African PG and DG.
As an example of how a custom double rifle can be configured for different sights, read on: