The riverside municipal Camping La Isla (Ginés Ponte s/n, tel. 02972/49-1461, US$4 pp) has good facilities but collects a small additional charge for showers, which have limited hours: 8–10 a.m. and 8–10 p.m.
The roadside Residencial Marisa (Bulevar Juan Manuel de Rosas 360, tel. 02972/49-1175, residencialmarisa [at] jdeandes [dot] com [dot] ar, US$21–28 s, US$27–39 d) has both doubles and bunks; breakfast is an inexpensive extra. Plaza San Martín’s basic Hostería del Montañés (San Martín 555, tel. 02972/49-1155, US$28 s, US$39 d) is a basic budget choice.
Aging but agreeable, the riverside Hostería Chimehuín (Coronel Suárez and 25 de Mayo, tel. 02972/49-1132, hosteriachimehuin [at] fronteradigital [dot] net [dot] ar, US$47 s, US$55 d) has 23 comfortable rooms, including a few slightly cheaper ones with shared baths, and a restaurant. Breakfast includes homemade scones and other specialties.
On Junín [1]’s northern outskirts, Hotel Alejandro Primero (Bulevar Juan Manuel de Rosas and Chubut, tel. 02972/49-1182, hotelalejandro1 [at] fronteradigital [dot] net [dot] ar, US$40 s, US$55 d) also has a restaurant, but the hotel staff are not well-trained.
Junín’s only four-star accommodations, the self-consciously rustic Río Dorado Lodge (Pedro Illera 448, tel. 02972/49-1548, www.riodorado.com.ar [2], US$98 s, US$160 d, with buffet breakfast; US$133 s, US$230 d, with half board, including wine and beer) has become the default option for foreign tour groups, especially but not exclusively for fly-fishing.
For pizza and pasta, plus sandwiches and empanadas, the traditional favorite is Roble Bar (Ginés Ponte 331, tel. 02972/49-1111, lunch and dinner daily). It has a credible challenger, though, in Pizzería Offa (Padre Milanesio 520, tel. 02972/49-2577, lunch and dinner daily).
Primarily a parrilla, the cavernous 
Ruca Hueney (Padre Milanesio 641, tel. 02972/49-1113, lunch and dinner daily) has a more diverse menu (try the pollo al ajillo, garlic chicken, US$6), good service even with large numbers of diners, and is now tobacco-free.
In an attractive building styled after Bariloche’s landmark civic center, the awkwardly named Centro de Turismo (Padre Milanesio 586, tel. 02972/49-2555, lunch and dinner daily) has a mostly standard Argentine menu; the standout item is the butter-grilled trout (US$7).
Across the plaza, Tío Tom (Lamadrid and San Martín, tel. 02972/49-2510) has Junín’s best ice cream.
Links:
[1] http://www.moon.com/destinations/argentina/northern-patagonia/the-lakes-district/junin-de-los-andes
[2] http://www.riodorado.com.ar