In the US, the key question would be whether the general concept (or "genus") is sufficiently described by the examples (or "species"). MPEP § 2163 is comprehensive, and summarises the current law on this point well. The key passage is:
The written description requirement for a claimed genus may be satisfied through sufficient description of a representative number of species by actual reduction to practice (see i)(A), above), reduction to drawings (see i)(B), above), or by disclosure of relevant, identifying characteristics, i.e., structure or other physical and/or chemical properties, by functional characteristics coupled with a known or disclosed correlation between function and structure, or by a combination of such identifying characteristics, sufficient to show the applicant was in possession of the claimed genus (see i)(C), above).
The issue is whether a person skilled in the art would understand the applicant to have invented, and been in possession of, the invention as broadly claimed.
So if you claim the broader concept (the genus), you should be fine providing you could successfully argue that the inventors invented the general concept to begin with, despite the description only including examples.
In Europe, this consideration would be basically the same (at least for sufficiency/support). However, there is a further European-specific consideration. If your specification as filed only contains a series of examples (without mentioning a generalised concept to link them), then you would never be able to cast a claim that covered the general concept. This would be an intermediate generalisation, which is impermissible. This only arises when amending the claims however, since the claims as originally filed are inherently based on the application as originally filed.
So what is the patent drafter to do?
You are required by US law to show that the inventors were in possession of the general concept. This could quite convincingly be done by explicitly describing the general concept, then providing some examples. For example,
A may be on any flat surface (such as A or B). In this case, A is on B.
A may be on any flat surface. In one embodiment, A is on B. In another embodiment, A is on C.
I think the difference between these is negligible, and purely a matter of style.
Either approach clearly provides a written description of the general concept, and therefore shows that the inventors were in possession of the general concept. In addition, it provides a basis for broadening amendments in Europe.
A blanket statement, such as "these are some alternative embodiments but not an exhaustive list" may help. However, it is relatively weak, and I would suggest that you should never plan to rely on general statements like this if you can be more specific.