What’s halacha l’maseh nowadays concerning washing hands after using the bathroom (in a case perhaps where there is more than just a toliet — a shower as well, or perhaps even a washer and dryer)?
It is permitted to wash hands today in a bathroom, where the bathroom is used for other matters.
Some, however, prefer to wash hands outside the bathroom, because of the possibility of ruach ra’ah.
However, Rav Shlomo Zalman Auerbach (cited in Mikra’ei Kodesh, Yom Kippur, p. 157, note 17) stated that there is no need today to be particular for halachos of ruach ra’ah that are not mentioned in the Gemara. Although he was referring to the halachah of walking 4 amos before netillas yadayim in the morning, the same can be applied here, with regard to netilas yadayim after entering a bathroom — and this is the more true concerning bathrooms that are used for other functions.
See Chazon Ish, Orach Chaim 17:4; Minchas Yitzchak 1:60 (explaining why it is permitted, but concluding that one should not be lenient under ordinary circumstances); Beis Shlomo 18; Levush Mordechai 182; Eretz Tzvi 110.