Their perception of a "hostal" is backpacking youngsters!
Keep in mind that "hostal" is a Spanish word meaning basic lodging where each guest has their own room, most often their own bathroom, and are (usually) family owned and operated budget hotels.
Here's where the confusion begins. The Spanish tourism board considers the English word "hostel" to be the same as "hostal" and so that's why I too consider them to be one in the same. They don't consider the word "hostel" to mean a "youth-hostel". We English speakers most often use the word "hostel" to mean dormitory-style lodgings or "youth-hostel". We've abbreviated "youth-hostel" to "hostel", but it's because of this abbreviation that we have the confusion.
I often see English speakers making the Spanish word "hostal" plural by adding an "S" to the end, "hostals", and this is incorrect. The plural of the Spanish word "hostal" is "hostales". And so, when speaking of Spanish "hostales" in English, the plural is "hostels". "Youth-Hostel" in Spanish is "Albergue Juvenil".
SO! (whew!) Your parents concern about the word "hostal" stems from not being familiar with the Spanish language. This is logical and natural.
jllawson is correct in that many hostels (or "hostales" in Spanish) do not have elevators, but many do (maybe 50%??). So if carrying bags up stairs is an issue be sure to ask or look on their website before you make reservations. Also, as I said above, these are basic lodgings with few having many decorations and "extras" like TV and phone. Most are smallish rooms which only contain your bed, a bedside table, usually a small table or desk with chair, an armoir (? -- a tall wooden piece of furniture into which you can hang/store clothing), a mirror, your bathroom, a window or balcony, and that's about it. I would think most older people, having lived a full life, require a little more room/reception comforts that aren't usually available from hostels. People of ALL ages stay in hostels in Spain, not just youngsters.
You might consider a Hostal-Residencia for a more "hotel-like" experience or even
Hostal Persal which seemed almost exactly like a real hotel when I visited it in October 2000 with the big lobby and check-in counter, sitting room, dining room, elevators, and decent/basic rooms. I know they're more expensive than most of the typical hostels, but not as expensive as your average low-cost hotel.
Good luck! Saludos, MadridMan
[ 02-21-2002: Message edited by: MadridMan ]