Although RS232 signals are nominally +/-12V, this is only to satisfy the maximum cable length specification. They can be +/-3V at the receiver end. I suspect RS232 was specified in the days when it was mainly in situations like carrying data from mainframe computer rooms to rooms full of terminals and printers a fair distance away. These days, RS232 cables are often just a couple of metres, so +/-12V is overkill. You could probably drive it with +/-5V.
It's arguable that most RS232 drivers are a waste of money to drive data just a couple of metres. Power supply requirements would be much simpler if the world had chosen RS485, which uses 5V differential signals, instead.
The MC1488 (4 Tx) and MC1489 (4 Rx) were the standard drivers for many years and have proved themselves adequate for most jobs. They are cheap (~79p each from Maplin) and common where +/-12V rails are available, such as inside PC motherboards.
The MAX202 (£2 from Maplin) is popular outside the PC where often only two lines (TxD, RxD) are needed for most applications, perhaps two more (RTS,CTS) for hardware handshaking. It also has a charge pump circuit to generate +/-10V for the transmitters.
Each fully buffered PC serial port requires 3 transmitters and 5 receivers. There are chips that have these exactly, but usually in small packages to suit laptops where there are no +/-12V rails. More common in DIP packages are chips that have 5 transmitters and 3 receivers - i.e. chips for devices that connect to a PC serial port - but that isn't what is needed here.
The SN75185 provides 3 transmitters and 5 receivers, but has no charge pump. They are cheap (in SO20, RS 355-3327 is 72p). This seems the best solution if there are +/-12V rails. If driven from a separate charge pump - which could be shared between several devices - then the CMOS version uses 160uA quiescent instead of 30mA, but at £2.79 each (1 off, RS Components 168-7383), they are dearer.
The ADM208 is like two MAX202 chips in a single DIP24 package. Thus one of these is enough for two serial channels with CTS/RTS handshaking. At £4.50 each (1 off, RS Components 234-7171), they cost a bit more than two MAX202 chips, but do save board space. RS also sell them in larger packs, so I guess they are a pretty popular item.
Most serial port projects have to buffer RS232 levels to TTL levels. If built into the same case as the host then such projects have direct access to the TTL signals, so the level-shifters can be discarded completely. In fact RS232 port were overwhelmingly used for mice and external modems. Mice have moved to PS/2 (and perhaps to USB). One can now buy modems that fit into DIP chip sockets, or Ethernet sockets. This seems far better than using an external modem just as big as the host system. Modems are now usually PCI cards or USB 'soft' modems requiring a pentium class CPU to to process the digitised signal by software, neither of which are suited to small systems.