Abu Dhabi has a genuine mid-range hotel market, most of it clustered downtown rather than on the resort islands.
Downtown Abu Dhabi and the areas just off the Corniche hold most of the city's value-oriented hotels — international budget and mid-range chains alongside independent business hotels, generally a fraction of Yas or Saadiyat's resort rates.
Budget hotels downtown won't have a theme-park-adjacent location or a private beach, but they put you closer to affordable local restaurants, public transport and the older city grid, which some travellers actually prefer.
A common strategy is booking a downtown mid-range hotel as your base and treating a night or two on Yas Island or Saadiyat as a deliberate splurge, rather than paying resort rates for the whole trip.